gradiometer survey to locate the ancient remains distributed to the northeast of the zoser pyramid,...

Archaeological ProspectionArchaeol. Prospect. 12, 61–68 (2005)Published online 31 January 2005 in Wiley InterScience (www.interscience.wiley.com). DOI: 10.1002/arp.245

GradiometerSurvey toLocatetheAncientRemainsDistributedto theNortheastoftheZoserPyramid,Saqqara,Giza,Egypt

H.ODAH,* T. F. ABDALLATIF, I. A. EL-HEMALYANDE. ABDEL-ALL

NationalResearch Institute ofAstronomyandGeophysics,11722Helwan, Cairo, Egypt

ABSTRACT Thewholearea to thenortheastof Zoserpyramid,Saqqara,Giza,Egypt, is characterizedby thedistri-butionofavarietyof tombstructuresof the1st and 2ndDynasties.Themainobjective ofundertakingagradiometer survey is to detect the ancient remainsaswell as otherarcheological featureshidden inthisimportantarea.Agradiometersurveywitharasterof0.5 m� 0.5mhasbeencarriedoutoverasur-face area of 100m�100m to achieve the purpose and the magnetic data were processed usingGeoplot software in order to obtainhighquality imagesof thehidden structures.The results obtainedshow thepresenceofinterconnectedlargetombstructurescomposedofmud-bricks; someotheran-cient roomsandwalls arealsopresent.Thehistoricalbackgroundof the studyarea confirmsthe exis-tenceofsuch tombstructures.Copyright� 2005 JohnWiley&Sons,Ltd.

Keywords: magnetic; gradiometer; ancient remains; Zoserpyramid; Saqqara;Giza

Introduction

Saqqara is characterized by an ancient and inter-esting history. In particular it was the main placeof burials of different dynasties, and also hasmore than ten pyramids including the mostfamous one (Zoser). The upstanding remainsmake Saqqara a great attraction for visitors andalso a significant role for the studies of research-ers and archaeologists. However, the wide arealocated northeast of the Zoser pyramid (Figure 1)contains no known remains and therefore is aninteresting place for investigating this site usinggeophysical surveys and techniques.

From the archaeological point of view, Egyptianand foreign archaeologists have studied manysites in the whole area of Saqqara. From thegeophysical point of view, however, fewer studies

have been done to investigate this important area.This encourages us to carry out a detailed mag-netic survey in order to assess the buried archae-ological features, which are expected to be foundat shallow depths, with less effort, time andmoney.

The magnetic method is the most widely usedmethod in prospecting for archaeology all overthe world (Aitken, 1974; Clark, 1990; Scollar et al.,1990). It has been used extensively atmany sites inEgypt (Abdallatif, 1998; Odah et al., 1998; Kameiet al., 2002; Ghazala et al., 2003; Herbich, 2003),including Saqqara (Elbassiony, 2001; Khozym,2003), and has produced impressive results forburied mud-brick structures and features (richwith magnetic minerals), which show a reason-ably high magnetic gradient.

A gradiometer survey has been applied in thepresent study in order to detect the archaeologi-cal features made of mud bricks or fire bricks.The application of the magnetic method willevaluate and help in the conservation of the

Copyright # 2005 John Wiley & Sons, Ltd. Received 1 September 2003Accepted 7 December 2004

* Correspondence to: H. Odah, Geomagnetism Laboratory,Liverpool University, Oxford Street, Liverpool L69 7ZE, UK.E-mail: [email protected]

hidden monuments at Saqqara by focusing onthe areas of interest.

Archaeological background

Saqqara (3000 BC), south of Cairo, covers an areaof 6 km from north to south and 1.5 km from eastto west. It is one of the largest and most impor-tant areas of archaeology in Egypt (Figure 2).Fifteen royal pyramids have been discovered inSaqqara. The most conspicuous landmark ofSaqqara is the step pyramid, the tomb of the3rd Dynasty ruler Zoser, which is probably theearliest major stone structure erected in Egypt(Baedeker, 1978).

Ancient Egyptians believed that deceasedrulers, their families and their courtiers wouldlive as they had on Earth if necessities wereprovided for their comfort and existence (Rogers,1992). So tombs were built and furnished withcomforts of the home: food, wine, pottery, furni-ture, games, weapons, small clay servants toperform necessary work, chests of garmentsand jewelry. In the afterlife, the Weighing ofthe Heart in the Hall of Judgment measured the

heart of the deceased against Truth, symbolizedby a feather of the goddess Maat. Travel to theafterlife took place on a solar or funerary boatthrough the sky (Rogers, 1992). The history ofSaqqara can be divided into the following mainstages:

Before pyramid construction (Dynasties 1 and 2)

The earliest royal name, which the archaeologistshave so far found at Saqqara, is that of Na’rmer,whom some Egyptologists equate with Menes,the legendary founder of Memphis. It isengraved on a porphyry bowl which, togetherwith thousands of other complete and fragmen-tary vessels of magnificent craftsmanship, wasdiscovered in one tomb of a later date, dating tothe reign of King ‘Aha (Menes according toanother school of thought, probably Na’rmer’ssuccessor).

Mastaba tombs of the 1st Dynasty lie in analmost continuous line along the eastern side ofthe large plateau north of the step pyramid ofZoser, above the modern village of Abusir. Thegenerally smaller private Mastaba of the largetombs of the 2nd Dynasty continued to be built in

Figure1. Locationmap of the Saqqara archaeological site, including the studyarea.

62 H. Odah et al.

Copyright # 2005 John Wiley & Sons, Ltd. Archaeol. Prospect. 12, 61–68 (2005)

an apparently haphazard way in the area west ofthe large tombs of the 1st Dynasty.

The pyramid builders (Dynasties 3 to 13)

Saqqara contains many interesting monuments,which have been recorded by many authors(Seton-Williams and Stocks, 1993). Nowadays,Saqqara has ten recorded royal pyramids, namedUnas, Horus Sekhemket, Zoser, Userkaf, Teti,Pepi I, Merenre, Djedkare Isesi, Pepi II andUserkare Khendjer. The most splendid of theseis the step pyramid of Zoser (mainly stone),which is considered as unique in the Egyptianarchitecture. It was built by Imhotep, the chief ofworks of Zoser and second king of the 3rdDynasty (Seton-Williams and Stocks, 1993).

The New Kingdom

Private tombs representing only the importantburials of the period immediately preceding therise of the 18th Dynasty have so far been foundat Saqqara. New Kingdom tombs, as knownat present, are concentrated in two areas ofSaqqara: (i) in the vicinity of the pyramid com-plex of Teti; (ii) in the area south of the causeway

of Wenis, defined by the ruins of the Copticmonastery of Apa Jeremias to the east and thepyramid enclosure of Sekhemkhet to the west.

The Late and Greco-Roman Periods

During the 26th Dynasty the designers of Egyptiantombs apparently achieved what they hadattempted in vain for the previous two millennia:they designed an almost completely secure tomb.The majority of the tombs of the Late and Greco-Roman Periods are near the step pyramid enclo-sure. However, the area of Saqqara also containsdifferent kinds of Mastaba. In the northwest ofthe area, Serapeum, the burial place of the Apisbull, can be seen; also called theHouse of Osarapisby the Ancient Egyptians (Seton-Williams andStocks, 1993).

Previous geophysical work

The whole site of Saqqara is an attractive placefor scientists and archaeologists, and studies atthis interesting area are continuous. Geophysicalinvestigations involving the application of geo-physical tools in detecting and evaluating the

Figure 2. The Zoser pyramid.

Gradiometer Survey Northeast of Zoser Pyramid 63


archaeological setting of the Saqqara archaeolo-gical site have been undertaken regularly.

In 1995, magnetic prospecting for archaeologyin Saqqara was applied by Myslivwiec andHerbich (the Polish Archaeological Center inEgypt) using a proton magnetometer, and pro-ducted very distinct results, especially for mud-brick burials included in sandy desert.

North of the Polish team area, exactly at thewestern side of Zoser pyramid, a gradiometersurvey has been carried using a fluxgate gradi-ometer over an area of 46 500m2 (Abdallatif,1998). The results obtained showed the presenceof tombs, kilns, ring gullies, ritual sites andremains of ancient walls.

At the end of 1999, a geophysical surveyincluding the magnetic method was carried outat the northeastern side of the Zoser pyramidusing a fluxgate gradiometer, over an area of10 000m2 (Elbassiony, 2001). The results pointedto the existence of three NW–SE orientated tombstructures made of mud bricks.

During of 2001, another geophysical studyincluding use of the magnetic method tookplace at the northeastern side of the Zoserpyramid, about 120m from the previous workof Elbassiony along the same direction. A flux-gate gradiometer was used in the magneticsurvey over an area of 12 000m2 (Khozym,2003). The results revealed the existence ofsimilar NW–SE orientated tomb structuresmade of mud bricks, with some wells anddissected walls.

It has been shown that the previous geophysi-cal work in Saqqara was dependent mainly onthe magnetic results and confirmed the possibi-lity of obtaining high quality results using mag-netism only. In the present work, therefore, themagnetic method was applied in order to locatethe ancient remains distributed at the northeast-ern part of the Zoser pyramid.

Magnetic data acquisition

The acquisition of magnetic data has been doneusing fluxgate gradiometer FM36 (GeoscanResearch, 1987) to cover a surface area of100� 100m (10 000m2). The study area wasdivided into 50 grids to facilitate the survey pro-

cess. The dimension of each grid was set to20� 10m. The field accessories such as measuringtapes, wedges, etc., were made of non-magneticmaterials. The tapes were marked at 0.5m inter-vals for accurate and fast survey. Routinely ingradiometer surveys, the instrument is balancedand zeroed at a selected zero reference point,normally situated in a stable magnetic field. Thefluxgate gradiometer (FM36) was set to a sensitiv-ity of 0.1 nT. Its height above the ground surfacewas about 0.15m. The measurements startedfrom the top left-hand corner of the study areaat 0.5m intervals with a zig-zag traverse pattern.The readings obtained were then downloadedto a microcomputer three times owing to thesmall memory of the instrument with respectto the surface area of the surveyed site. The totalnumber of readings of the study area is 40000.

The preliminary results obtained are repre-sented in a grey colour scale using Geoplotsoftware to show the acquired gradiometer rawdata (Figure 3). The gradient of the vertical com-ponent of the geomagnetic field ranges from�14.0to þ14.0 nT (The actual range after clipping theobtained data). The resultant magnetic imagelooks unclear and disturbed with noise that makesit difficult to interpret. However, it shows somefeatures requiring some processing steps to bemore enhanced and smoothed for interpretation.

Magnetic data processing

The gradiometer survey is normally accompa-nied by some field errors and noise owing to therelatively high sensitivity of the instrument,weather conditions at the time of the survey,and also the experience of the operator. Removalof these errors and noise is significant in ourpresent study in order to enhance the presenta-tion of the data obtained and also to facilitate theinterpretation process.

The field errors and noise in the present studyare mainly summarized as tilting of the FM36,discontinuities at grid edges, striping of traversesand displacement of the obtained features. How-ever, enhancement of the data obtained has alsobeen extended to removing the effects of scat-tered iron objects and hidden high-frequencyobjects.

64 H. Odah et al.


Geoplot software (Geoscan Research, 1994) hasbeen used to process the acquired gradiometerdata. Geoplot has many functions for this pur-pose, such as zero mean grid, zero mean traverse,despiking, destaggering, low-pass filter and clip-ping.

The grid edge discontinuities have been trea-ted by the application of zero mean grid (ZMG)with a threshold value¼ 2.5 standard deviation,and the stripes between traverses have beenremoved by the application of zero mean tra-verse (ZMT) with least mean square fit.

The study area was cleaned of any obviousiron materials before starting the corrections.The data were clipped initially (�14/14 nT) toremove the high frequencies resulting from anyexpected surface iron spikes. Also, the despikefunction (K) was applied for more enhancementand good presentation.

Stagger defects arising due to a simple mis-positioning of the instrument along the zig-zagtraverse have been corrected using the destaggerfunction, which displaces the even numberedtraverse of the specified grid in the X directionby an integer amount (positive or negative).Figure 3 shows obvious displacements for the

resultant archaeological features in several grids.These displacements have been corrected byseparately dealing with each grid. An even tra-verse shift of þ1m has been applied to correctthe displacements at grids A3, A4, A5, B2, C2 andE10, and a traverse shift of �1.5 has been appliedto correct grid D10. Also, a traverse shift of 1.5has been applied for grids A8, A10, B9 and B10,and a traverse shift of 2 has been applied forgrids A9, B8, E4, E5 and E6.

To smooth the magnetic data of Figure 3, aGaussian low-pass filter has been applied toremove the high frequencies as well as to enhancethe weak anomalies of deep archaeological fea-tures. The low-pass filter parameters were set toX and Y radii¼ 2. The resultant processed mag-netic image is presented in Figure 4. It is consid-ered the best magnetic image following theapplication of all the processing functions.

Results and discussions

The application of the magnetic method to mud-brick remains at Saqqara appears to have pro-mising results, supported by some previous

Figure 3. Magnetic image showing the rawdata of the studyarea at Saqqara.



studies around the study area. In the present studythe archaeological features obtained (Figure 5)show similar anomalies, trends, thickness, elon-gation and polarities. This suggests the continua-tion of the same regime ruler (1st and 2ndDynasties) in this important area.

Moreover, the resultant magnetic image of thenortheast area of the Zoser pyramid (Figure 5)has shown buried archaeological remainsformed of mud bricks represented by near-sur-face features with enhanced magnetic suscept-ibilities. However, the study area in generalshows no traces of any past industrial activity.The image shows the existence of linear featuresparallel to each other and on the same axis(NW–SE). The black features distributedthroughout the study area are caused by highmagnetic gradients resulting from mud-brickremains, which may refer to thick mud-brickwalls surrounding tomb structures. The eightfeatures of interest have been highlighted onFigure 5.

Feature A is represented by a positive highmagnetic gradient anomaly with respect to thesurrounding medium. It occupies grids C8, C9,D8, D9 and D10 and is produced by mud-brick

features constructed in a rectangular form withdimension of about 30� 12m and average thick-ness of about 3m. It is orientated NW–SE with noclear shaft or opening from the traced sides onthe image. However, the breaks in the anomalymay indicate small openings. Moreover, themissing side at the southern border of the imagemay contain an opening or entrance gate. It isimportant to confirm that the walls of the sur-rounding excavation areas contain no openingsfor entrance, which may refer to defensiverequirements.

Feature B is also represented by a positive highmagnetic gradient anomaly. It occupies grids C5,C6, C7, D5, D6 and D7 and generally has nearlythe same characters as feature A with smallerdimension of about 27� 13m and thickness ofabout 2m. The construction of this feature isdivided into two parts, the main part located atgrids D5, D6 and D7, and another adjoiningsmall part located at grids C6 and C7. The mainpart has an opening of about 2mwidth located atits northwestern side and may lead to the inter-nal burial room. The smaller part has an openingof about 1.5m width located in its southeasternwall.

Figure 4. Magnetic image of the studyarea at Saqqara afterapplication of the processing functionsof the Geoplot program.

66 H. Odah et al.


Features C, D and E are represented by posi-tive moderate to high magnetic gradient anoma-lies. They are generally characterized by theirsmall size with respect to the other features; C isabout 10.5� 5.5m, D is about 10� 5m, and E isabout 10� 8m. Three openings have noticed infeatures (C) and (D): one in C and two in D. Noopenings are found in feature E.

Feature F is represented by a positive moder-ate magnetic gradient anomaly. It occupies gridsA9 and A10 and its dimensions are about17� 9.5m, with a thickness of about 1.5m. Threeopenings can be noticed on its two longest sidesand may lead to the internal burial room. How-ever, it is difficult to decide which one of them isthe main gate and which is just a destroyed part.

Feature G is represented by a positive highmagnetic gradient anomaly. It is located in gridsA6, A7 and A8 with dimensions of about25� 17m and thickness of about 1.5m. Thisfeature is divided internally into different

partitions, which are mostly destroyed. How-ever, a clear entrance gate is noticed its north-eastern side with a width of about 4m. Thisentrance gate leads to another gate of the samewidth. It may be some kind of construction forcamouflage.

Feature H is represented by a positive highmagnetic gradient anomaly. It is located in gridsB3, B4, B5, C4 and C5. Its dimensions are about24� 17m, with an average thickness of about2m. It has a main gate at its northeastern sidewith an average width of about 2.5m which maylead to the internal burial room.

In addition to the features discussed pre-viously, some other features represented by posi-tive magnetic anomalies (black spots) may benoted in grids B9, B10, C8, D3, D5, D6, E1, E8,E9 and E10. We tend to interpret them as sepa-rated parts of destroyed walls and not tombs.This is supported by the existence of similarsurface wall features. However, some of them

Figure 5. Magnetic image of the studyarea showing themud-brick remainsderived from themost expressive image of Figure 4.



may lead to interpretation as tombs particularlywith regard to their size and form, which agreeto a large extent with known tombs found atSaqqara and some other sites.

Conclusions

The aim of the present study was to detect theancient remains located at the northeastern sideof Zoser pyramid using a gradiometer survey.The archaeological site of Saqqara generallyshows a variety of royal pyramids, tombs andmud-brick structures with different ages fromthe 1st Dynasty to the 26th Dynasty.

The study area in general contains completeand dissected mud-brick walls surroundingtomb structures and burial rooms. This is similarto some other sites beside the study area. Thedissected mud-brick walls may point to randomdigging by non-specialists and/or robberactions.

The probability that these mud-brick remainsare mainly tomb structures containing intercon-nected underground burial rooms is supportedby earlier excavation work near the study area.

The presence or absence of openings in someremains is a mystery amongst a huge assembly ofancient Egyptian mysteries.

Thus, we conclude that the area located north-east of the Zoser pyramid contains mud-brickremains, which represent the normal continua-tion of the old kingdom tombs of the 1st and 2ndDynasties. Moreover, the detection of theseremains using gradiometer survey confirms thegreater efficiency of magnetic methods thanother geophysical tools in locating mud-brickfeatures in sandy soil. Although this was thereason for using only the magnetic survey, wealso recommend that other geophysical methodsbe applied for more detailed surveys, especiallyon such important archaeological sites.

Acknowledgements

The authors thank the Department of Geomag-netism and Geoelectricity, National Research In-stitute of Astronomy and Geophysics (NRIAG)

for kind support with field instruments, cars andrequired facilities. Also, many thanks to theAuthority of Egyptian Archaeology for theirkind permissions and field inspectors.

References

Abdallatif TF. 1998. Magnetic prospection for somearchaeological sites in Egypt. PhD thesis, Facultyof Science, Ain Shams University.

Aitken MJ. 1974. Physics and Archaeology, 2nd edn.Oxford University Press: Oxford.

Baedeker K. 1978. Egypt from A to Z, Handbook forTravelers. Jarrold and Sons: Norwich.

Clark JA. 1990. Seeing Beneath the soil: ProspectionMethods in Archaeology. B.T. Batsford: London.

Elbassiony AAA. 2001. Geophysical archaeoprospec-tion in Saqqara and Qantir areas, Egypt. Masterthesis, Faculty of Science, Ain Shams University.

Geoscan Research. 1987. Instruction Manual Version1.0 (Fluxgate Gradiometer FM9, FM18, FM36).Geoscan Research: Bradford.

Geoscan Research. 1994. Instruction Manual 1.01(Geoplot 2.01). Geoscan Research: Bradford.

Ghazala H, El-Mahmoudi AS, Abdallatif TF. 2003.Archaeogeophysical study on the site of TellToukh El-Qaramous, Sharkia Governorate, EastNile Delta, Egypt. Archaeological Prospection 10:43–55.

Herbich T. 2003. Archaeological geophysicsin Egypt: the Polish contribution. ArchaeologiaPolona 41: 13–55.

Kamei H, Atya MA, Abdallatif TF, Mori M,Hemthavy P. 2002. Ground-penetrating radarand magnetic survey to the west of Al-ZayyanTemple, Kharga Oasis, Al-Wadi Al-Jadeed(New Valley), Egypt. Archaeological Prospection 9:93–104.

Khozym A. 2003. Geophysical prospection of somearchaeological sites in Saqqara area, Giza, Egypt.Master thesis, Faculty of Science, Ain ShamsUniversity.

Odah H, Abdallatif TF, Hussain AG. 1998. Micro-magnetic prospecting to delineate the buriedsolar boats in Abydos area, Sohag, Egypt. Journalof Environmental Sciences. (Mansoura University,Egypt) 16: 121–133.

Rogers A. 1992. New Complete Guide of Egypt, LaFotometalgrafica Emiliana Spa: Bolonga; 146 pp.

Scollar I, Tabbagh A, Hesse A, Herzog I. 1990.Archaeological Prospecting and Remote Sensing. To-pics in Remote Sensing. Cambridge UniversityPress: Cambridge; 375–516.

Seton-Williams V, Stocks P. 1993. Blue Guide—Egypt. Atlas, Street Atlas of Cairo, Maps, Plans andIllustrations. A&C: London and W. W. Norton:New York.

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gradiometer survey to locate the ancient remains distributed to the northeast of the zoser pyramid,...

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