Research - Materials

THE EFFECT OF THE GEOLOGICAL NATURE OF SIWA

OASIS ON THE DETERIORATION

OF ARCHAEOLOGICAL AND HISTORICAL BUILDINGS

Sampling was made on the saline limestone, Al-Kurshef and its mortar for the determination of their compo-nents, elements and current status.

The results have shown that the halite salt is the main component of saline limestone and Al-Kurshef.

The Oasis is characterized by the presence of salt lakes, as the climate is a very dry continental desert. The rain falls many times, and thus salt deposits are formed from halite salts, gypsum and other salts. The salts, mud and other deposits are forming a local saline building material that ancient people from Siwa used extensively in their unique-style buildings (called al-Kurshef), which is a mixture of mud and sediments. 

The salty nature and very low rainfall are most prominent in the preservation of the historical Shali castle. The geological nature of Siwa Oasis had the greatest impact on the damage of these ma-terials. The limestone in the village of Aghurmi, Siwa Oasis, the Temple of Oracle contains a large percentage of salts in addition to the clay minerals of Smectite, Illite and kaolin and the presence of marine fossils.

The use of saline building materials in Siwa Oasis is one of the unknown building techniques that were used in the village of Shali.

This architecture is characterized by the use of blocks of salts taken from the nearby salt lakes and covered with a layer from clay mortar filled with salts, and this technology is still present today, as it represents the exploitation of resources from the local surrounding environment.

This research aims to study saline limestone, which is a unique type of limestone, where the proportion of salts exceed 30% of the components of the stone and this type is found in Siwa Oasis only in Egypt.

The study also aims to identify a basic building material in Siwa that is still used to this day, which is Al-Kurshef, where the Shali Castle was built from it. It is found only in Siwa, according to its geological nature.

Siwa is characterized by surface saline deposits, where these deposits are formed in a heterogeneous unit of dolomite, black clay, anhydrite salts, halite and other salts, which are among the weakest rock components, and these salts are crystallized after being deposited in a very arid environment and in the presence of shallow lakes

Siwa Oasis is characterized by a desert climate, characterized by mild winters and extremely hot summers, the average daily temperature varies from 10.6 ° C in January to 38.8 ° C in July, the rate of evaporation ranges from 4.32 millimeters to 13.54 millimeters, and the average annual rainfall reaches 10.43mm. Siwa is also considered a very dry region, as the annual rates of evaporation are high, reaching approximately 30,000 mm

It has been shown through the previous results that halite salt is the main compound of building materials in Siwa Oasis, whether it is Al-Kurshef or saline lime- stone, and this reflects the geological nature of the Siwa Oasis, which is characterized by the presence of evaporators (salts), this salt is considered a weak point in the building material. It is a hygroscopic salt that is soluble in water in humid climates.

The effect of the saline nature of the lime-stone on the damage and deterioration of the Oracle temple

1.Fragmentation and loss of limestone due to expo-sure of halite salt to cycles of dissolution and crystal-lization.

2. The occurrence of many fissures and cracks in the walls of the temple.

3. The temple is built on the Aghurmi rock, which suffers from weakness and cracking, and is structur-ally threatened by collapse at any time, and therefore this threatens the safety and survival of the temple, and this rock is part of the geological nature of Siwa Oasis

7. CONCLUSION

Siwa Oasis is characterized by the traditional archi-tecture of saline building materials, the effect is the result of its environment, as Siwa Oasis is character-ized by unique building materials based on salts and these materials, which in turn are the result of the ge-ological nature of Siwa Oasis. The ancient architect exploited the building materials of saline limestone in the building of Oracle Amun temple, as well as Al-Kurshef in the construction of the Shali castle. The use of local woods such as palm trunks to support these historic buildings, suffers from deterioration, frag-mentation and damage due to their weakness caused by the salty nature of the building materials.

As cracks of all kinds and degrees are spread, which exposes them to annihilation and extinction, it is recommended to carry out restoration operations such as reinforcement, as well as isolation of tradi-tional building materials from sources of moisture to preserve this unique cultural heritage for future gen-erations. Sodium chloride salt (which is a major com-ponent of these materials) is considered one of the salts. The multiple cycles of dissolution and crystalli-zation - solubility in water and crystallization during drought of this salt - threaten this unique cultural her-itage, which is a testament of the ancient Egyptian