a geotechnical investigation of sandstone degradation...

A GEOTECHNICAL INVESTIGATION OF SANDSTONE DEGRADATION IN LUXOR, EGYPT Adam Sevi, Department of Civil Engineering – University of Missouri-Rolla, Rolla, Missouri, USA Dr. Ahmed Ismail, Illinois Geological Survey, Champaign, Illinois, USA Dr. Richard Stephenson, Department of Civil Engineering – University of Missouri-Rolla, Rolla, Missouri, USA ABSTRACT The temples of Luxor, Egypt constitute 25% of the worlds known antiquities. Accelerating deterioration of the foundation stone comprising the lower portion of many antiquities has lead to concern for the long term stability of these monuments. Foundation stone appears to degrade in the presence of water seeping upward through the ground and into the stone. This dampness is often accompanied by a white efflorescence that can be seen at the surface. Affected stone exhibits a complete loss of cohesion and effectively crumbles away at the stone’s surface. This field and laboratory investigation was performed to establish the makeup of the soils, efflorescence, stone and groundwater involved in this degradation process. Samples were collected and analyzed using x-ray diffraction, scanning electron microscope, moisture content, hygroscopicy, thin section, and ion chromatography. Results from this investigation, the mechanism of degradation and possible methods of limiting this destructive process are summarized in this paper. RÉSUMÉ Les temples de Luxor, Egypte constituent 25% de les antiquités connues par mondes. Détérioration d'accélération de la base en pierre la comportement de la partie inférieure de beaucoup d'antiquités a pour mener à concerner pour la stabilité à long terme de ces monuments. La pierre de base apparaît à dégradez en présence de l'eau s'infiltrant vers le haut par la terre et dans pierre. Cette humidité est souvent accompagnée d'une efflorescence blanche qui peut être vu sur la surface. La pierre affectée montre une perte complète de cohésion et s'émiette efficacement loin sur la surface de la pierre. Ces champ et laboratoire la recherche a été effectuée pour établir le maquillage des sols, efflorescence, pierre et eaux souterraines impliquées dans ce processus de dégradation. Des échantillons ont été rassemblés et analysé en utilisant la diffraction de rayon X, microscope électronique de balayage, humidité contenu, hygroscopicy, sections minces, et chromatographie d'ion. Résultats de ceci recherche, le mécanisme de la dégradation et méthodes possibles de limitation ce processus destructif sera récapitulé en cet article. 1. INTRODUCTION Deterioration of the stone comprising the foundations of many temples in the Luxor area has been observed to be accelerating in recent years. Foundation stone appears to be degrading in the presence of dampness within the stone and a white efflorescence seen on the stone surface. Affected stone exhibits a complete loss of cohesion and effectively crumbles away at the stone surface. The water appears to be seeping up through the ground below the foundations and continuing up into the foundation stone by capillary action. The groundwater table has been found to be between three and nine meters below the surface throughout much of Luxor, and is the source of the up seeping water (Ismail, 2003). The effected foundation stone is generally sandstone that was imported to Luxor from the Silsila Gorge Quarry, located approximately 60 km north of Aswan. This is considered one of the best quarries for quartizitic sandstone in Egypt however, these sandstones tend to

be porous silica sand based stone with little to no anthogenic overgrowth. Groundwater is drawn up into the sandstone blocks by capillary rise as seen in Figure 1 at the Luxor Temple. Once exposed to the area’s hot and dry climate, the water quickly evaporates. When the upward seeping water evaporates, any salt held in solution is left behind at the point of evaporation. As this process continues, the salts accumulate both in and on the soil and stone. The salt accumulation further contributes to capillary ability through hygroscopicy (the attraction of water), and osmotic flux, effectively accelerating the water transport to the site. These accumulating salts, or efflorescence, can be seen on the foundation stone of many temples of the Luxor area, including the Habu City seen in Figure 2. However, the salt crystallization inside the pore spaces of the sandstone is the proven mechanism of sandstone decay (Lewin, 1983). Removing these accumulating salts from stone and underlying soils is of paramount importance in the preservation of the temples of Luxor.

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Figure 1. Ahmed Ismail measures capillary rise in a reconstructed wall of the Luxor Temple.

Figure 2. Efflorescence formed at the Habu City on the West Bank of the Nile River near Luxor.

1.1 Historical Setting The Nile River valley is considered by many to be the cradle of modern civilization. Due to the area’s annual flooding, this valley has been among the most fertile of agricultural lands for centuries. These annual floods have historically deposited nutrient rich sediments throughout the Nile flood plain. Another direct effect of this flooding has been that the fresh water would dissolve any salts accumulated in the floodplain and transport them down the Nile River and to the Mediterranean Sea. This symbiotic relationship between the people, crops, civilization and the Nile River brought about the world’s best preserved ancient civilization. The completion of the Aswan High Dam in 1970 has greatly tamed the Nile River below Aswan. No longer is the Luxor area regularly inundated by the now historic flooding. The modern city of Luxor, historically known as Thebes, is located 670 km south of Cairo, Egypt, some 900 km from the confluence of the Nile River joining the Mediterranean Sea. Thebes reached its height of power, influence and architectural accomplishment during the New Kingdom from 1570 BC to 1090 BC. With a population of approximately one million people, Thebes controlled an area from Sudan to present day Libya. While many pharaohs ruled over Thebes, the “Thebian Triad”, including the local gods Amun, Mut and Chons, are considered the source of inspiration behind the architectural accomplishments of Thebes. The vast majority of Luxor’s temples were built using sandstone mined from throughout Egypt. The stone was typically cut and barged to Thebes where it was moved onto the building sites using large logs as rollers. In order to erect the massive walls, temporary mud brick ramps were built. Later the mud brick ramps were removed revealing the finished structure for ornamentation. After the Late Dynastic period, Thebes came under the control of Persian invaders and later welcomed Alexander the Great of Macedonia as a liberator from Persian rule in 332 BC. Throughout the following centuries the wonders of Thebes continued to be reworked, however Thebes was no longer the focus of Egyptian architecture. The upper Nile, including Thebes, was largely used as an agricultural area until the 19th century and the Thebian rediscovery by Napoleon. 1.2 Geological Setting The Luxor area is located in the fertile Nile River valley of Egypt. The fertile land extends for up to 15 km on either side of the Nile River and is limited to the east and west by tall cliffs. The river flows generally from south to north, through the middle of the valley in Luxor. The flood plains of the Nile River valley are covered with fine-grained fertile sediments delivered by the historic annual flooding of the Nile River. In several excavations in the Luxor area, soils have been found to contain pieces of pottery to depths over eight meters. Through studying this broken


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pottery, archeologists are able to date the sediments, thus dating the covering of Luxor’s antiquities. Sediments at the surface in Luxor are generally characterized as clayey silts. These clayey silts contain abundant nutrients and have been the mainstay of agriculture in the Nile valley throughout history. In the Luxor area, the ground elevations vary from about 72 meters above mean sea level in the vicinity of the Nile River to 400 meters above mean sea level on the adjacent plateaus. The fertile valley floor is intersected by numerous irrigation canals designed to deliver fresh water from the Nile to crops on both the east and west banks of the river. As noted by Dr. Rushdi Said the “Basin irrigation, as it was practiced in Egypt for thousands of years, was one of the most effective methods of utilizing the river. It can be started by the sparsest of populations and support in wealth a multitude of people, while the direct labor of cultivation is reduced to an absolute minimum,” (Said, 1981). The Nile River has its origin in the Equatorial and Ethiopian Plateaus to the south of Egypt. Three major tributaries supply the vast majority of the water that flows through Luxor. The longest tributary of the Nile River is known as the White Nile. The White Nile forms the drainage for the majority of Northeastern Africa. The upper tributaries of this river extend into Kenya, Tanzania and Uganda. These tributaries are collected into and flow through a series of lakes in Uganda. The White Nile then flows through Equatoria and into southern Sudan and the great central plateau of Tanganyika. From these headwaters the White Nile then flows into the “Sudd”. The Sudd is a region of swamps and marshes extending several hundred kilometers in width. Here several other subsidiary rivers join the drainage system. Due to extensive evaporation and transpiration, little volume is gained by the Nile in this section. The name Sudd is derived from Arabic, meaning blockage or impasse. This is in reference to the difficulty involved in navigating the area due to extensive erosion blockage of the waterway. The Sudd is typified by the many rotting chunks of vegetation and soil which become detached from the banks and float down river. It is the remains of this organic material that is later deposited throughout the Nile flood plain, and has allowed the Nile based civilizations to prosper. Many other civilizations have waned once their irrigation canals became clogged with silt. Sediments carried by the Nile River, however, are of such fine quality that that siltation is almost non-existent. The extremely fine nature of these sediments is largely responsible for the long history if strong civilizations along the Nile River. The White Nile is joined by the Blue Nile in Khartoum, Sudan. It is the annual flooding of these two rivers that is largely responsible for the Nile’s annual rise and fall in Egypt. Once entering Egypt the Nile receives very little additional water as the climate in southern Egypt is extremely dry. Throughout the river valley in Egypt canals have been constructed for the purpose of agricultural irrigation. Excess irrigational water commonly infiltrates the ground, contributing to regional

groundwater. It is evident that water leaked into the groundwater table later rejoins the Nile further downstream. The Nile generally acts as a drain throughout most of Egypt as it does in the Luxor area. The geological origin of the Nile River in Egypt is still widely debated. Among the prevailing assessments is that the Nile River in Egypt is of a tectonic origin followed by successive erosion by the river. After the building of the Aswan dam, the river’s seasonal fluctuations, and subsequent deposition of fine-grained soils and nutrients is severely limited. The majority of the populated area of Egypt, including Luxor, is downstream of Aswan. The Aswan dam generally holds Lake Nasser at 180 m above mean sea level. 1.3 Hydrogeological Setting Regional groundwater flow in the Luxor area is in a south to north direction, parallel to the Nile River. The hydraulic gradient is approximately 1X 10-4 m/m. Since the construction of the Aswan High Dam, the Nile River has acted as a drain to the groundwater table in the Luxor area. Groundwater flow in the proximity of the Nile River is toward the river on both the east and west sides at a gradient of about 5 X 10-3 m/m (RIGW, 1991). Seasonal fluctuations in groundwater flow are primarily influenced by local irrigation practices. These practices generally follow the yearly rise and fall of flow in the Nile River. Groundwater is present below the effected temples of Luxor at a shallow depth in the semi-confined aquifer known as the Quaternary aquifer. This aquifer is composed of well-graded sand and gravel overlain by some 1 to 25 m of silty clay fluvial deposits. This aquifer is considered semi-confined by the overlying silty clay, but is open at its eastern and western extents where the aquifer becomes phreatic. The source of groundwater in this aquifer is primarily infiltration from municipal water systems, excessive agricultural irrigation and leaking irrigation canals. Located at a greater depth and extending to the eastern and western limit of the Nile valley is the Plio-Pleistocene aquifer. This aquifer is composed of sand, gravel and clay and is also considered semi-confined. The aquifer is phreatic at the eastern and western extents of the valley. However, the vast area of this aquifer is fully confined underneath the fertile area of the Nile valley in Luxor. The salt content of groundwater in the Luxor area generally increases with distance from the Nile River. The salinity of the Nile River is typically within the 231 to 307 ppm range, and is considered to be of fresh water quality. Similar concentrations are found in irrigation canals, due largely to the fact that the direct source of these canals is the Nile River. The shallow Quaternary aquifer underlying the central part of the Nile valley has been found to have salinity values between 250 and 1499 ppm. This body of water is noted as a good source of fresh water for both drinking and irrigation. The deeper Plio-Pleistocene aquifer, extending beneath the Nile valley from the eastern to western plateaus contains


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higher salinity from 1383 to 4211 ppm (El-Hosary, 1994 & Ismail, 2003). 2. FIELD AND LABORATORY INVESTIGATION

A field and laboratory program was performed to gather information regarding the deterioration of foundation stone in the Luxor area. Sampling was limited to bulk samples taken from non-sensitive sites located near affected antiquities. This study was intended to be a preliminary study with a limited field and laboratory program. The sites visited and samples collected in no way cover the vast number of effected antiquities throughout Luxor, nor fully cover variations in soil, groundwater, building stone and degraded stone at the locations sampled. This field program was intended to gain an understanding of the area’s soil and groundwater qualities and to identify the composition of the affected foundation stone and efflorescence. 2.1 Field Investigation Soil, stone and degraded stone sampling was carried out in an effort to quantify the capillary ability, moisture content and chemistry of these materials. Soil samples were collected in the vicinity of the Luxor and Karnak temple, located on the east bank of the Nile River within the town of Luxor, and at the Memnon Statues, Ramsseum, and Habu City on the west bank. Stone samples were collected from several salt affected, but, non-sensitive sites for thin section study. Groundwater samples were collected at locations close to the Habu Temple and the Karnak Temple. A soil water sampler also known as a suction lysimeter was used to sample water from damp soil. The soil water sampler consists of a porous ceramic cup attached to the bottom end of a PVC tube. The top end of the PVC tube is closed with a rubber stopper with a small neoprene hose extending to a hand operated vacuum pump. The tube is placed, porous cup down, in an excavated hole. The hole is then back filled with silica flour and sealed at the surface using bentonite. A vacuum is then applied through the neoprene hose and the system is left while groundwater is accumulated through the porous cup. This technique allows groundwater sampling directly from damp ground in areas of interest. Unfortunately, the system was vandalized while collecting the second sample and no further sampling could be performed. 2.2 Laboratory Investigation A laboratory program was designed to find the constitutive makeup of soil, stone, degraded stone and efflorescence samples collected. Moisture content, grainsize distribution, hygroscopicy, scanning electron microscope and x-ray diffraction testing was performed on select soil and rock samples. Rock samples were also viewed using thin sectioning techniques. Ion chromatography was performed on water and groundwater samples.

2.2.1 Moisture Content Sampling was carried out during the month of June when local conditions in Luxor are hot and dry. All samples were taken from areas where no agricultural activity was evident. Due to these conditions, it is believed that all water contained in these soil samples was attracted from the groundwater table and not from irrigation or rain. It was observed in the field that fine-grained soils were often damp at the ground surface, while more course soils were generally dry. This observation is consistent from the view that grain size is a primary factor in a soil’s capillary ability. At several different sites soil samples were taken from a white crusty layer of soil at the surface with a separate sample taken from a few centimeters underneath. In all cases the surface soils were found to contain considerably higher water contents than the underlying soil. In one case, a difference of almost 17% was found between the water content of the crusty surface soil and underlying soils located a few centimeters below. 2.2.2 Hygroscopicy

Hygroscopicy is the property of a substance to readily absorb moisture from the surrounding atmosphere. While hygroscopic moisture accumulation is not a common test, the ability of soil to attract water from the atmosphere indicates that the soil would also attract moisture from the underlying groundwater table. While numerous hygroscopicy testing methods have been presented, no single testing procedure enjoys a widespread performance record. Upon review of the subject, a simple method of exposing the samples to a non-controlled, but relatively stable environment was chosen. This method allowed weighing of the samples without removing them from a known and continuously measured atmosphere. For this investigation soil and stone samples were subjected to hygroscopic moisture accumulation testing as follows. The testing location was selected which allowed atmospheric conditions to prevail. The state of Missouri, USA regularly endures extensive humidity spells in the summer months with relative humidity staying above 95% for several days at a time. The test was started in the evening when the winds are generally calm and the air is cooling, keeping humidity at the dew point or 100% humidity. In preparation for this test, samples were first dried and weighed to establish the dry weight of the respective samples. Samples were then exposed to atmospheric conditions. The samples were weighed at different time intervals while atmospheric conditions were recorded. The test was run several times during prolonged spells of humid weather to ensure repeatability and to observe any salt migration that would occur during successive exposure to humidity and then drying. The majority of the soil and stone samples tested acquired surprisingly large amounts of water from the atmosphere. Several soil samples attracted 8% to 10% of their weight in water. Crushed stone samples from the


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Ramesseum area and a degraded stone sample from the Karnak area attracted 5.7% and 4.3% hygroscopic moisture respectively. Most notable was a soil sample collected from a centimeter below the ground surface near Habu City. This soil sample attracted almost 25% of its dry weight in water when exposed to a saturated environment. Additionally, during the successive runs of the test, a hard white surface formed on the top of many samples. In some cases the surface was not penetrable with the tip of a pencil. 2.2.3 Grainsize Distribution/ Capillary Ability Grain size analysis was performed on selected soil samples in order to calculate the estimated capillary ability of the soil. The calculation of capillary ability was performed using the simple equation for capillary rise (hc) developed by Allan Hazen in 1894.

10eD

Chc = [1]

The values for the void ratio (e) and C coefficient were estimated as follows. A void ratio range of 0.4 to 0.6 was estimated based on the Extended Casagrande Soil Classification table for “SF: sand with excess fines”. The empirical C coefficient was varied from 0.01 to 0.05. Using an estimated void ratio of 0.4 and the maximum C coefficient of 0.05, typical soils from the area were found to have an estimated capillary ability of over 16 meters. Given the situation in Luxor; with the hot/ dry atmospheric conditions, high salinity near the surface causing osmotic flux, temperature gradients, and soil hygroscopicy, it is quite possible that this estimate using the maximum C coefficient is representative of what could occur in the field. 2.2.4 Scanning Electron Microscope

A scanning electron microscopy was used to identify the elemental components of soil, stone and degraded stone samples. This method identifies the makeup of the sample by individual elements present. The bulk of the soil and stone samples were comprised of silicone and oxygen indicating a silicon dioxide (SiO2), or quartz sand makeup. Silicon dioxide is a strong and chemically stable compound with a hardness of 7 on the Mohs scale. Weathering of silicone dioxide is considered “slow” indicating a geological time scale. Additionally, magnesium, sodium and chlorine are present in many samples tested. These elements can combine to form the compounds magnesium salt (MgCl2), and sodium chloride (NaCl), which are hygroscopic compounds that contribute to the overall capillary ability of a soil. 2.2.5 X-Ray Diffraction X-ray diffraction was performed on select samples to identify the crystals present in a given sample. This technique can be used to identify specific crystalline structures, but gives no indication of the amount of the identified compound present. Analysis was performed to

identify the compounds silicon dioxide (SiO2), sodium chloride (NaCl), sodium carbonate (Na2CO3) and hydrous calcium sulfate (CaSO4 2(H2O)). Quartz (SiO2) was expected to be the primary crystalline compound composing the majority of soil and stone in the Luxor area. Salt, sodium carbonate and gypsum are hygroscopic compounds that were suspected to be accumulating in surface soils and stone. Silicone dioxide was found to be present in all samples tested. The only sample found to not contain salt (NaCl) was an intact piece of very competent sandstone from the vicinity of the Memnon statues. Crystalline salt is present throughout the soils and stone of Luxor, on both the east and west banks of the Nile River. Hygroscopic compounds appear to be largely limited to salt (NaCl) with sodium carbonate and gypsum being detected in only a few samples. 2.2.6 Thin Section

Thin sections of stone samples were prepared and analyzed to study variations in stone matrix and geological composition. Stone stabilization was necessary in the preparation of thin section mounting because several stone samples were extremely friable. Blue dye was added to the stabilizing agent to highlight void spaces in the stone samples. Stone cutting was performed using a water based oil lubricant; therefore the study of soluble salts was not included in the investigation of thin sections. The majority of stone samples were found to be composed of silica sand based sandstone, often with some rock lithic fragments included. Differences in sand particle size, rounding and post depositional cementing indicate different depositional environments. Comparing two stone samples; one collected from east of the Karnak Temple and the second from the vicinity of the Memnon Statues appear to be of completely different geological origins. The sample from near the Karnak Temple was observed to have a porosity of 40%, and be primarily made up of loosely joined rock lithic fragments. Extreme care was necessary when handling this sample as the stone was extremely friable. Conversely, a stone sample from the vicinity of the Memnon Statues exhibits porosity of 5%, and is of very solid composition. The primary component of this sample was silica sand with extensive anthogenic overgrowth forming a solid stone matrix. This stone is likely to remain intact for millennia to come and is of little concern in antiquity degradation. Comparison of these two stone samples can be seen in figures 3 and 4.


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Figure 3. Thin section of stone sample from vicinity of Habu City.

Figure 4. Thin section photo of rock sample collected from the vicinity of the Memnon Statues. 2.2.7 Ion Chromatography

Ion chromatography analysis was performed on groundwater samples to detect chloride ions indicating an ability for this water to form salt (NaCl) efflorescence upon evaporation. In addition, nitrate and phosphate ions are of interest as these ions indicated the groundwater may be affected by local agricultural activity.

The water sample collected from an open water source near the Habu temple was found to be of fresh water quality. Chloride content was 74 ppm, nitrate below 50 ppm and negligible phosphate content was detected. However, a sample collected using suction techniques; collecting ground water directly from the soil near the Karnak temple was found to have extremely high chloride concentration. This water sample was found to contain 36,429 ppm chloride. Additionally, this sample contained 126 ppm nitrate and trace phosphate. The groundwater sample collected from damp soil in the shallow subsurface near the Karnak temple is the most definitive confirmation that salts are concentrating in groundwater in the upper extents of the area’s soils. The exceedingly high concentration of chloride, at 36,429 ppm is typical of seawater. Additionally, the presence of both nitrate and phosphate indicate that this water has likely been affected by agricultural activity. 2.3 Summary of Findings and Conclusions To quantify the materials involved with the degradation process soil and stone samples were collected from the vicinity of effected temples. Highlighting the important findings of this investigation are the following: first, both soil and stone throughout the Luxor area are primarily composed of the elements silicone and oxygen indicating a silicone dioxide (SiO2) or quartz makeup, second, crystalline salt (NaCl) was found to be present in almost all soil and stone samples, third, salt is also the main component of the efflorescence which accompanies degradation throughout Luxor, and fourth, many of the soil and stone samples exhibited the ability to attract moisture from the surrounding atmosphere known as hygroscopicy. Groundwater was also sampled as in most cases dampness accompanies degradation. A groundwater sample taken directly from damp ground in the vicinity of the Karnak temple was found to contain more than 36,000 ppm chloride. This high presence of chloride indicates that salt efflorescence will form at the point of evaporation of this water. The dampness present at the ground surface and on foundation stone in Luxor is capillary water that has migrated above the groundwater table by means of capillary action. Crystalline salt (NaCl) is present on the ground surface throughout the Luxor area in the form of efflorescence. This salt is deposited at the point of evaporation of chloride rich capillary water. The capillary ability of soil was estimated through sampling and testing techniques. Tests indicate some soils in the Luxor area are estimated to have a capillary ability as high as 16 meters. Once the capillary water is exposed to the area’s hot/dry climate evaporation occurs. It is at this point that the transported salts are left to crystallize in and on the soil or stone. Salt deposits both in and on sandstone has been proven to cause irreparable damage when allowed to crystallize within the pore spaces of sandstone. This mechanism


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requires a salt solution that is allowed to flow up into the sandstone by capillary action. Once inside the sandstone the transporting capillary water evaporates. At this point the transported salt comes out of solution as efflorescence on the surface of the sandstone, or in crystalline form within the pore space of the sandstone. This formation of salt crystals within the pore spaces of the sandstone has been proven to create a blister lifting the outer layer of the stone (Lewin, 1982). Once the sandstone is blistered, it is then easily eroded by wind or physical abrasion. Additionally, if one porous stone in a wall fails by these means the entire wall will collapse over time. A failure of this nature is depicted in figure 5 showing an incremental wall collapse at the Ramesseum. Historically, these salts would be washed out of the surface soil in the Nile flood plain with the annual floods. Since the completion of the Aswan high dam in 1970, however, the Nile no longer swells over its banks in the Luxor area. This loss of an annual flushing of the salts from the flood plain has lead to a buildup of salt at the ground surface in the Luxor area. This buildup of salt at the surface is continuing, and possibly accelerating with no mechanism for removing the salts from the area’s soil and stone. The ingredients for sandstone degradation are all present in the Luxor area. Effected stone is generally porous silicated sandstone. Near surface groundwater contains an alarmingly high concentration of chloride. Finally, atmospheric conditions are hot and dry for a large portion of the year, allowing efficient water evaporation. These conditions provide a situation that is conducive to the degradation of sandstone. 3. FUTURE REASEARCH

Future research should focus on either the removal of salts from sites of interest or the blockage of capillary rise. This could be achieved by adding fresh water at the surface to saturate the surface soils and drive a hydraulic gradient downward to the regional ground water table. The salts would then be removed from the site with regional groundwater flow. Different water application techniques and flow rates could be tested to find the most effective method for removing the harmful salts. Care must be taken to avoid possible vegetation growth that could be more harmful than the salts already present. Capillary blockage could be accomplished by the injection of a chemical barrier in the soil, perhaps using electrical osmosis techniques. 4. ACKNOWLEDGEMENTS The writers of this paper would like to extend our appreciation to the many individuals working at the Egyptian National Research Institute of Astronomy and Geophysics for their assistance throughout this project. Additionally appreciation is extended to Dr. Neil Anderson of the University of Missouri-Rolla Department of Geology and Geophysics for supplying the impetus for this project.

Figure 5. Progressive wall failure due to a single block failure at the Ramesseum on the West Bank near Luxor. References Barton, D., (1938) Discussion: The Disintegration and

Exfoliation of Granite in Egypt, Journal of Geology, Vol. 46, pp. 109-111.

El-Baz, F., (1993) Saving the Sphinx, Geotimes, May, pp. 13-17.

El-Hosary, M., 1994, Hydrogeological and Hydrochemical Studies on the Luxor Area, Master of Science Thesis, Menoufia University.

Gill, V. and Dale, T., (1974) Topsoil and Civilization, University of Oklahoma Press.

Hawass, Z., (1993) The Egyptian Monuments: Problems and Solutions,” Proceedings of the International

RILEM/ UNESCO Congress of Conservation of Stone

and Other Materials, Vol. 1, pp. 19-26. Hazen, A., (1896) The Filtration of Public Water-Supplies,

John Wiley and Sons, New York, New York, USA. Hutcheon, W. L., 1958, “Moisture Flow Induced by

Thermal Gradients within Unsaturated Soils,” Highway Research Board Special Report 40 – Water and It’s Conduction in Soils, pp. 113-133.


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Ismail, A., 2003, Geophysical, Hydrological, and Archaeological Investigation in the East Bank Area of Luxor-Southern Egypt, University of Missouri-Rolla, USA, PhD Thesis.

Lewin, S. Z., (1982) The Mechanism of Masonry Decay Through Crystallization, Conservation of Historic

Stone Buildings and Monuments, Committee on Conservation of Historic Stone Buildings and Monuments, Washington D. C., National Academy Press, pp. 120-144.

Research Institute for Groundwater (RIGW), (1991) Hydrogeological Map of Egypt - Luxor, Scale 1:100,000, First edition.

Rzqsa, S., Owczarzak, W. and Spychalski, W., (1993) Methodological Advances used to Analyze Maximum Hygroscopic Water in Soils of Different Structure,” Int.

Agrophysics, 7, pp. 213-220. Said, R., (1981) The Geological Evolution of the River

Nile, New York, Springer-Verlag Inc.. Sevi, Adam, 2002, Geotechnical Investigation of

Sandstone Degradation of Antiquities in Luxor, Egypt, University of Missouri-Rolla, USA, Masters of Science Thesis.

Wust, R. A. J., (2000) The Origin of Soluble Salts in Rocks of the Thebes Mountains, Egypt: The Damage Potential to Ancient Egyptian Wall Art,” Journal of

Archaeological Science, 27, pp. 1161-1172.


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