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Journal of Archaeological Science 40 (2013) 1158e1164

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Journal of Archaeological Science

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Quarries and transportation routes of Angkor monument sandstone blocks

Etsuo Uchida a,*, Ichita Shimoda b

aDepartment of Resources and Environmental Engineering, Faculty of Science and Engineering, Waseda University, Ohkubo 3-4-1, Shinjuku, Tokyo 169-8555, JapanbDepartment of Architecture, Faculty of Science and Engineering, Waseda University, Ohkubo 3-4-1, Shinjuku, Tokyo 169-8555, Japan

a r t i c l e i n f o

Article history:Received 24 May 2012Received in revised form21 September 2012Accepted 26 September 2012

Keywords:Angkor monumentsSandstoneQuarryTransportation routeCanalCambodia

* Corresponding author. Tel.: þ81 3 5286 3318; faxE-mail address: weuchida@waseda.jp (E. Uchida).

0305-4403/$ e see front matter � 2012 Elsevier Ltd.http://dx.doi.org/10.1016/j.jas.2012.09.036

a b s t r a c t

Sandstone blocks are the main construction materials used in the Angkor monuments in Cambodia.However, a thorough study of the quarries has not yet been carried out. We conducted a field investi-gation of sandstone quarries from the Angkor period at the southeastern foot of Mt. Kulen, which isapproximately 35 km northeast of the Angkor monuments. As a result, we discovered more than 50sandstone quarries. On the basis of the measurements of magnetic susceptibilities and thicknesses (stepheights), we found that they were quarried at different times. These four quarrying areas were identifiedas the quarries D to G inferred by Uchida et al. (2007). In addition we investigated a canal that wasidentified on satellite images, connecting quarry sites at the foot of Mt. Kulen to the Angkor monuments.The field investigation suggests a high probability that the canal was used for the transportation ofsandstone blocks from Mt. Kulen.

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1. Introduction

Sandstone, laterite, and brick are the main construction mate-rials in the Angkor monuments. Three types of sandstones arefound in the monuments, but a gray to yellowish brown sandstone(feldspathic arenite) is most common among them (Uchida et al.,1998). In this study, we conducted an investigation of quarriesand transportation routes of the sandstone.

The gray to yellowish brown sandstone consists mainly ofquartz, plagioclase, potassium feldspar, biotite, muscovite, and rockfragments of approximately 0.2 mm diameter. No differences werefound in constituent minerals and bulk chemical compositions ofthe sandstone among the monuments (Uchida et al., 1998; Ku�ceraet al., 2008). However, the sandstone showed differences inmagnetic susceptibility. On the basis of the magnetic susceptibility,Uchida et al. (1998, 2003, 2007) inferred seven different sandstonequarries from the Angkor period. In addition, the magneticsusceptibility measurements made it possible to estimateconstruction periods and sequences of the monuments.

The gray to yellowish brown sandstone was derived from theTerrain Rouge Formation (the Phu Kradung Formation in Thailand)of the early to middle Jurassic (Garnier, 1873; Saurin, 1954; Delvert,1963; Meesook et al., 2002). The Terrain Rouge Formation isdistributed widely in eastern Cambodia in addition to Thailand,

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Laos, and Vietnam. In Thailand, there are no Khmer monumentswhich used the gray to yellowish brown sandstone as a construc-tion material. However, it was used for Wat Phu in Laos andMy Sonin Vietnam. In northern Cambodia, the gray to yellowish brownsandstone was used for major monuments such as Koh Ker, PreahKhan of Kompong Svay, and Banteay Chmar as well as the Angkormonuments (Uchida et al., 2010). The nearest outcrop of the gray toyellowish brown sandstone to the Angkor monuments is located atthe southeastern foot of Mt. Kulen. Several sandstone quarries ofthe Angkor period have been previously discovered there (Garnier,1873; Saurin, 1954; Delvert, 1963; Carò and Im, 2012). However,a thorough study of the quarries has not yet been done. Wetherefore conducted a field investigation at the southeastern foot ofMt. Kulen. In addition, on the basis of satellite images (Googleearth), traces of a canal (consisting of bank, canal and river) con-necting quarry sites at the southeastern foot of Mt. Kulen to theAngkor monuments were identified. Under the hypothesis that thecanal was used for the transportation of sandstone blocks, weconducted a field investigation of this canal. This paper reportsresults of the field investigation.

2. Sandstone quarries

Garnier (1873) first postulated that the gray to yellowish brownsandstone used in the Angkor monuments was supplied from thesoutheastern foot of Mt. Kulen. Afterwards Delvert (1963) con-ducted a field investigation of sandstone quarries. He found several

E. Uchida, I. Shimoda / Journal of Archaeological Science 40 (2013) 1158e1164 1159

quarries at Trapeang Thmar (Thmo) Dap, Au Mealea, Phnom Bey(Bei), and other areas. The distribution of sandstone quarries isroughly shown in a map by Boulbet (1979). Recently Rocks (2009)and Carò and Im (2012) reported several sandstone quarries fromthe Angkor period. However, the number of sandstone quarriesdiscovered until now is not enough for the construction of all theAngkor monuments. Thus it is expected that there are abundantundiscovered sandstone quarries. In this context, we conducteda field investigation of sandstone quarries at the southeastern footof Mt. Kulen. As will be discussed later in detail, an eastewest linearstructure 2.4 km long was observed at the southeastern foot of Mt.Kulen on satellite images. Under the hypothesis that this linearstructure may be a transportation route for the sandstone blocks,we conducted a field investigation around it. We discovered morethan 50 sandstone quarries of various scales in the area. The loca-tions of each quarry are indicated in Fig. 1. Photos of representativequarries are shown in Fig. 2.

Most of the quarries discovered to date are distributed in theeastern to northern areas of the linear structure mentioned previ-ously. The scale of the quarries ranges from 10 to 50 m in width. Asmentioned previously, there are no differences in constituentminerals and bulk chemical compositions of the gray to yellowishbrown sandstone among the Angkor monuments, but the averagemagnetic susceptibilities changed over time as elucidated byUchida et al. (1998, 2003, 2007). Therefore a magnetic suscepti-bility measurement was conducted in each quarry in order todeduce the period in which each quarry was used. The magneticsusceptibilities were measured randomly at 5e25 places in eachquarry depending on its scale. The measurements were carriedout on surfaces as flat as possible, avoiding weathered surfaces.The average values are summarized in Table 1. In addition to the

Fig. 1. Topographic map showing the bank with an east-west orientation at the southeasternhave been used as a transportation route. The numbers of quarries correspond to those in Tasandstone blocks, the quarries can be classified into four areas (Areas A to D). MS: a range

magnetic susceptibilities, shape, especially thickness, of the sand-stone blocks also changed over time (Uchida et al., 2005). Thereforestep heights of the quarry sites instead of thicknesses of thesandstone blocks were also measured (Fig. 1 and Table 2). Beforethe Angkor Wat period, sandstone blocks had a square end anda thickness of 40e50 cm, except for some sandstone blocks in thePreah Ko and Bakheng periods. After that, the thickness of thesandstone blocks tended to thin over time, that is, to 30e35 cmin the Angkor Wat period except for Angkor Wat itself and WatAthvea (40e55 cm), and to 20e30 cm in the Bayon period(Uchida et al., 2005). Although these values are thicknesses of thesandstone blocks used in the monuments, the thickness of thesandstone blocks cut from the quarries is estimated to have been atleast 10 cm thicker than these values.

On the basis of the average magnetic susceptibilities andthicknesses (step heights), the investigated sandstone quarries canbe classified into four areas, shown in Fig. 1. Fig. 3 shows histo-grams of magnetic susceptibilities of the sandstones for Areas Ato D. Area A is along the eastern part of the previously mentionedlinear structure, and corresponds to the areas Toek Lick and ThmaAndong identified by Carò and Im (2012). In Area A, the averagemagnetic susceptibilities and thicknesses (step heights) of thesandstone blocks range from 1.6 to 2.5 � 10�3 SI units and from 50to 60 cm, respectively. These data suggest that the quarries in AreaA were used in the Preah Ko or Khleang to Baphuon periods(including Pre Rup) and correspond to quarries A or D of Uchidaet al. (2007) (Table 2). Taking into consideration that Bakong isthe only large scale monument in the Preah Ko period, it is quitepossible that the quarries in Area A were used in the Khleang toBaphuon periods and correspond to quarry D of Uchida et al.(2007).

foot of Mt. Kulen and the distribution of sandstone quarries. The bank is considered toble 1. On the basis of the magnetic susceptibilities and thicknesses (step heights) of theof magnetic susceptibilities (� 10�3 SI unit), and TH: a range of thicknesses.

Fig. 2. Photos of the sandstone quarries located at the southeastern foot of Mt. Kulen. (a) quarry No. 22 in Area A, (b) quarry No. 10 in Area B, (c) quarry No. 45 in Area C, and (d)quarry No. 31 in Area D.

Table 1Positions (longitude and latitude) of the sandstone quarries at the southeastern foot of Mt. Kulen and average magnetic susceptibilities of sandstones at each quarry. For theaverage thickness (step height) of the sandstone blocks see Fig. 1 and Table 2.

Quarry No. Latitude Longitude Av. M.S.a Quarry No. Latitude Longitude Av. M.S.a

1 13� 290 09.3200 N 104� 120 19.5300 E 0.68 29 13� 290 25.2100 N 104� 110 09.2400 E 2.082 13� 290 29.4600 N 104� 120 18.8000 E 1.28 30 13� 290 26.1400 N 104� 110 09.6800 E 2.013 13� 290 30.2600 N 104� 120 19.5600 E 2.70 31 13� 290 25.5000 N 104� 110 11.9400 E 2.004 13� 290 33.5400 N 104� 120 08.8900 E 2.67 32 13� 290 24.0400 N 104� 110 13.3800 E 1.765 13� 290 32.8000 N 104� 120 07.8600 E 2.82 33 13� 290 23.5500 N 104� 110 14.7700 E 1.636 13� 290 33.9300 N 104� 120 07.2400 E 4.53 34 13� 290 23.8300 N 104� 110 16.7100 E 1.687 13� 290 20.9500 N 104� 120 16.4500 E 2.09 35 13� 290 24.5500 N 104� 110 16.7500 E 2.058 13� 290 20.1000 N 104� 120 18.0500 E 3.31 36 13� 280 52.7000 N 104� 130 33.0000 E 0.779 13� 290 19.3600 N 104� 120 18.4200 E 2.99 37 13� 290 00.6300 N 104� 120 07.7700 E 1.4410 13� 290 18.5800 N 104� 120 17.0600 E 3.57 38 13� 290 01.7200 N 104� 120 10.3300 E 1.4311 13� 290 18.0800 N 104� 120 17.8600 E 3.38 39 13� 290 02.7700 N 104� 120 08.1800 E 0.7512 13� 290 15.4000 N 104� 120 16.7600 E 3.50 40 13� 290 04.5700 N 104� 120 06.3500 E 0.4913 13� 290 14.9300 N 104� 120 18.3900 E 1.05 41 13� 290 02.4400 N 104� 110 58.6200 E 0.8014 13� 290 15.2500 N 104� 120 19.3900 E 1.98 42 13� 290 03.4900 N 104� 110 57.5400 E 1.0915 13� 290 14.4800 N 104� 120 18.3400 E 1.15 43 13� 290 02.7000 N 104� 110 55.0600 E 0.3316 13� 290 09.5000 N 104� 130 21.5000 E 1.99 44 13� 290 19.2000 N 104� 110 52.1700 E 0.7717 13� 290 00.3000 N 104� 130 04.5000 E 2.46 45 13� 290 20.1700 N 104� 110 51.4200 E 0.9918 13� 290 01.2000 N 104� 120 17.4000 E 0.97 46 13� 290 18.1700 N 104� 110 46.7800 E 0.5419 13� 280 39.0000 N 104� 120 25.7500 E 2.49 47 13� 290 17.1400 N 104� 110 37.9900 E 2.0920 13� 280 43.6100 N 104� 120 31.8000 E 1.61 48 13� 290 20.3500 N 104� 110 35.1500 E 1.7921 13� 280 46.1400 N 104� 120 33.4400 E 1.92 49 13� 290 09.8200 N 104� 110 50.8300 E 0.8822 13� 280 48.0300 N 104� 120 41.8200 E 2.14 50 13� 290 03.6300 N 104� 120 16.1300 E 0.7123 13� 280 50.1900 N 104� 120 43.8600 E 2.62 51 13� 290 09.2000 N 104� 130 18.5000 E e

24 13� 290 04.6300 N 104� 120 42.5500 E 1.90 52 13� 290 02.5000 N 104� 120 57.9000 E e

25 13� 290 07.8600 N 104� 120 42.5500 E 2.21 53 13� 290 05.2000 N 104� 120 59.9000 E e

26 13� 290 09.3500 N 104� 120 41.0400 E 4.26 54 13� 290 04.7100 N 104� 120 06.9700 E e

27 13� 290 03.7900 N 104� 120 27.6600 E 3.64 55 13� 290 00.9900 N 104� 110 54.5700 E e

28 13� 290 17.8300 N 104� 110 05.2300 E 1.70 56 13� 290 01.9900 N 104� 110 53.2700 E e

a Average magnetic susceptibility (� 10�3 SI unit).

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Table 2Correlation of Areas A to D of sandstone quarries discovered in this study to the Quarries A to G inferred by Uchida et al. (2007).

Period InferredquarriesA to Ga

Average magneticsusceptibilities inquarries A to G(10�3 SI unit)a

Thickness in centimetersof sandstone blocks usedin the monumentsb

Areas of quarriesfound in this study

Average magneticsusceptibilitiesin Areas A to D(10�3 SI unit)

Thickness in centimeters ofsandstone blocks (step height)cut from Areas A to D

Preah Ko Quarry A 1.1e2.3 30e50Bakheng Quarry B 1.0e9.0 20e45Transitional Quarry C 2.3e3.0 40e45Bakheng to

BaphuonQuarry D 1.1e2.4 40e45 Area A 1.2e2.5 50e60

Angkor Wat Quarry E 2.8e4.3 30e50 Area B 2.6e4.5 45e60Early Bayon Quarry F 0.7e1.4 25e35 Area C 0.3e1.4 30e50Late to post

BayonQuarry G 1.2e3.1 25e35 Area D 1.6e2.1 30e40

a From Uchida et al. (2007).b from Uchida and Ando (2001).

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Area B is in the northeastern part of the linear structure. In AreaB, the average magnetic susceptibilities are characteristically high,2.6e4.5 � 10�3 SI units (except for quarries Nos. 2 and 7, 1.3 and2.1 �10�3 SI units, respectively), and the thicknesses (step heights)are 45e60 cm. Judging from these facts, it is considered that thequarries in Area B were used in the Angkor Wat to early Bayonperiods and correspond to quarry E of Uchida et al. (2007) (Table 2).

Area C is located in the north of the east part of the linearstructure. The magnetic susceptibilities in this area are as low as

Fig. 3. Histograms of magnetic susceptibilities of the sandstone in Areas A to D. MS:magnetic susceptibility, and SD: standard deviation.

0.3e1.4 � 10�3 SI units except for a quarry No. 14 (1.98 � 10�3 SIunits) and the thicknesses (step heights) are also relatively low, 30e50 cm. These characteristics suggest that the quarries in this areawere used in the main Bayon period and correspond to quarry Fof Uchida et al. (2007) (Table 2).

The quarries in Area D (Don Enn) are in the northwestern part ofthe linear structure. The average magnetic susceptibilities range1.6e1.2 � 10�3 SI units and the block thicknesses (step heights) are30e40 cm. The average magnetic susceptibilities in Area D aresimilar to those in Area A. However, the thickness (step height) ofthe sandstone blocks is much thinner in Area D compared withArea A. On the basis of these facts, it is considered that thequarries in Area D were used in the late Bayon period andcorrespond to quarry G of Uchida et al. (2007) (Table 2). Theseresults suggest that the sandstone quarrying activity moved overtime from the eastern area to the northwestern area of the linerstructure. It seems that the quarries were concentrated in certainareas during certain periods, and that sandstone blocks weresupplied from multiple quarries in a certain area.

The depth of the quarries varies from place to place, and rangesfrom less than 1 m up to 6 m. A depth of 1e3 m is most typical. Thelargest quarry found to date is quarry No. 45, which reaches 50m inwidth and 6 m in depth. The sandstones of the quarries in Area Bhave high average magnetic susceptibilities corresponding to thesandstone blocks used in the monuments of the Angkor Wat toearly Bayon periods. However, their scale seems not to besufficient to supply all the sandstone blocks used in these periodswhen the representative large scale monuments of Angkor Wat,Ta Prohm, and Preah Khan were constructed. Thus it is expectedthat many other large scale quarries remain undiscovered aroundArea B. The total amount of sandstone blocks cut from thequarries in Areas A to D is not estimated yet. This kind ofsurveying is thus indispensable to estimate the total volume ofsandstone blocks supplied from these quarries.

3. Transportation route of sandstone blocks

Previously it was believed that sandstone blocks of the Angkormonuments were transported from the southeastern foot of Mt.Kulen to Tonle Sap Lake via canal, and then supplied to the Angkormonuments by going up the Siem Reap River via Tonle Sap Lake(Lunet de Lajonqière, 1911: Boisselier, 1952). In this scenario, thetransportation distance reaches 90 km, and also it is obliged to goup the Siem Reap River. This is not an easy transportation route. Onthe basis of satellite images, we found a waterway (consisting ofcanals and partly of rivers) connecting the southeastern foot of Mt.Kulen to the Angkor area, and also an eastewest linear structure2.4 km long at the southeastern foot of Mt. Kulen. The existence of

E. Uchida, I. Shimoda / Journal of Archaeological Science 40 (2013) 1158e11641162

the waterway was suggested by Evans et al. (2007) andHendrickson (2007). We conducted a field investigation to confirmwhether these structures were used for the transportation ofsandstone blocks.

3.1. Sandstone block transportation route at the southeastern footof Mt. Kulen

An eastewest linear structure was observed on satellite imagesof the southeastern foot of Mt. Kulen as shown in Fig. 1. As it washypothesized that this linear structure was a transportation routefor sandstone blocks, we conducted a field investigation to confirmthis. The east end of this linear structure is located at N 13� 280 5800

and E 104� 120 1500 with an altitude of 93 m, and the west end is at N13� 290 0500 and E 104� 100 5900 with an altitude of 90 m. The lengthof the linear structure is 2.4 km. The central part has a slightly loweraltitude and the lowest point is 82 m in altitude. The field inves-tigation revealed that the linear structure forms a bank which isabout 2.5 m higher than the surrounding area. Because an 800 mlong depression was observed adjacent to the bank to the north inthe eastern part and some water remains in the depression, it ispossible to consider that it was a waterway. However, the depres-sion is not observed in the western part of the bank structure andthe central part of the bank has not yet been investigated due todense forest. As mentioned previously, many sandstone quarries

Fig. 4. The transportation route of sandstone blocks, connecting the quarry sites at the sointerpretation of the references to colour in this figure legend, the reader is referred to the

are distributed around the bank in the eastern and northern areas.Several small sandstone quarries exist adjacent to the bank. Thus, itis highly possible that this bank was used as a transportation routefor sandstone blocks. As the relatively old quarries (Area A) arelocated near the east end of this bank structure, it is supposed thatthis bank was constructed in the early Angkor period.

3.2. Waterway connecting Mt. Kulen to the Angkor monuments

On satellite images, we found a line starting from Point 1 (N 13�

280 2200, E 104� 100 4700, and 81 m in altitude) 1.3 km south of thewest end of the aforementioned bank and continuing to the Angkormonuments (Fig. 4). Because this line was hypothesized to bea canal used for transportation of sandstone blocks from thesoutheastern foot of Mt. Kulen to the Angkor monuments, wecarried out a field investigation. The route is shown in Fig. 4 witha red line. Judging from the satellite images, it seems to consistmainly of canals and partly of rivers. The result of the field inves-tigationwill be described in what follows. Photos are also shown inFig. 5.

Point 1 to Point 2: The 2 km area between Point 1 and Point 2(N 13� 270 5100, E 104� 090 3900) forms an embankment 2 m high.A depression 20 m wide is adjacent to this embankment to thenorth. It was assumed that this depressionwas used as a waterway,but no water remains in this depression. The altitude of Point 1 is

utheastern foot of Mt. Kulen to the Angkor monuments, shown with a red line. (Forweb version of this article.)

Fig. 5. Photos of the transportation route of sandstone blocks. The location of each point is shown in Fig. 4. (a) The starting point (Point 1) of the transportation route to the Angkormonuments. An embankment about 2 m high is accompanied by a depression to the north. (b) The turning point (Point 2) of the embankment into a canal. (c) Appearance of thecanal at Point 3. The height from the bottom of the canal to the top of the embankments reaches 6 m. (d) Appearance of the canal at Point 7. The cross section of the embankment isexposed by a road cut. (e) Appearance of the canal at Point 11. The canal is about 20 mwide with an embankment 2 m high to the south, and (f) appearance of the canal at Point 12.

E. Uchida, I. Shimoda / Journal of Archaeological Science 40 (2013) 1158e1164 1163

81m and that of Point 2 is 78m. The central part is lower than Point1 and Point 2, and the lowest point is 72 m in altitude. As watercannot flow from Point 1 to Point 2, the sandstone blocks may havebeen transported by a road on the embankment.

No artificial structure related to stone transportation wasobserved between the west end of the bank at the southeasternfoot of Mt. Kulen and Point 1.

Point 2: The depression continuing from Point 1 deepenssuddenly at Point 2, and changes into a canal, in which waterremains. It is postulated that the sandstone blocks were trans-ported by a road on the embankment to Point 2 and then by a canalfrom Point 2. Several sandstone blocks are scatted at Point 2.

Point 2 to Point 3: The area between Point 2 and Point 3 (N 13�

270 5300, E 104� 080 4000) is a canal with embankments on both sides,where water remains in most places. The embankments havea height of 2e3 m, and the canal has a depth of 5e7 m from the topof the embankments to the bottom of the canal and a width of 20e30 m. Because the altitude at Point 3 (81 m) is slightly higher thanat Point 2 (78 m), the canal around Point 3 was dug deeper than thesurrounding areas.

Point 4: Instead of a canal, several rivers run in the area aroundPoint 4 (N 13� 270 3500, E 104� 060 4800).

Point 5 to Point 6: There is a canal between Point 5 (N 13� 270 1600,E 104� 050 3700) and Point 6 (N 13� 270 1800, E 104� 050 2200), similar tothat in the area between Point 2 and Point 3. The height of the

embankments is 1.5 m and the width is around 20 m. The canal isdestroyed in the west part of this area and is used as a fish farm atpresent. There is a river instead of a canal in thewest end of this fishfarm.

Point 7: A canal was confirmed at Point 7 (N 13� 270 4000, E 104�

040 4900). A cross section of the embankments can be observed atthis point because of the construction of a road through theembankment. The height of the embankments is about 1.5 m.

Point 8: At Point 8 (N 13� 270 0700, E 104� 020 2300), an embank-ment with a height of about 2 m is observed on the south side, butno embankment on the north side. We can see a depression withwidth of around 20 m at this point, but no water was observedthere. On satellite images, a river can be seen south of this point,and water runs in this river at present.

Point 9: At Point 9 (N 13� 250 5500, E 104� 000 1400), there isa meandering river instead of a canal.

Point 10: The river joins the Roluos River at Point 10 (N 13� 250

2800, E 103� 590 2900). The Roluos River runs southward and reachesTonle Sap Lake through the Roluos monuments. Chau Srei Vibol,which is 3 km east of Point 10, is connected to Point 10 with a canal.A long canal continues westward from Point 10 to the Angkormonuments.

Point 10 to Point 14: There is a canal between Point 10 and Point14 (N 13� 250 4100, E 103� 530 2600). The canal shows an eastewestorientation in the area between Point 10 and Point 13, then turns

E. Uchida, I. Shimoda / Journal of Archaeological Science 40 (2013) 1158e11641164

to the northwest, and continues to the west of Banteay Kdei (Point14). The 2 m high south embankment is used as a road at present,but the north embankment is not clearly observed. Thewidth of thecanal is 20e25 m. The canal is filled with soil in many places,although water remains in several places up to 2 m deep.

4. Considerations and summary

On satellite images, we found a linear structure 2.4 km long atthe southeastern foot of Mt. Kulen. As the result of a field investi-gation, it was proved to be a bank. Abundant sandstone quarries aredistributed around the bank. On the basis of the measurements ofmagnetic susceptibilities and thicknesses of sandstone blocks (stepheights), the quarries can be classified into four areas, and it wasrevealed that the quarrying activity moved from the eastern area tothe northwestern area of the bank over time. These facts suggestthat the bank was used as a transportation route for the sandstoneblocks from the beginning of the Angkor period.

Judging from its location, it is considered that the canal (partlya river) starting from a point 1.3 km south of the west end of theaforementioned bank (Point 1) and continuing to the Angkormonuments was used for the transportation of sandstone blocksquarried from the southeastern foot of Mt. Kulen. This canal isalmost the shortest route from quarry sites to the Angkor monu-ments, and the distance is 34 km. Sandstone blocks can be easilytransported by this canal from quarry sites to Phnom Bok and ChauSrei Vibol situated on the way to the Angkor monuments; to theRoluos monuments by going down the Roluos River; and also toPhnom Krom by going down the Siem Reap River. Because it is notnecessary to go upstream in the canal and river, it seems thatsandstone blocks were transported efficiently by this route. Fromsuch a point of view, the transportation route suggested previouslyfrom the southeastern foot of Mt. Kulen, via a canal to Tonle SapLake, and going up the Siem Reap River to the Angkor monumentsseems less probable than that proposed in this paper.

Acknowledgments

This study was supported financially in part by a Grant-in-Aidfor Scientific Research from the Ministry of Education, Culture,Sports, Science and Technology of Japan (Project No. 23401001

(E. Uchida)). The manuscript was improved by useful suggestionsby two anonymous reviewers.

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