The Citadel of Bam:
The Largest and Oldest Raw Mud Brick of the World in Heart of Iran Deserts

Mohammad Hady Far Poor¹ & H.R. Krouse²

¹ Soil Science Department, Faculty of Agriculture, Shahid Bahonar University of Kerman, Kerman, Iran
e-mail: farpoor@mail.uk.ac.ir

² Department of Physics and Astronomy, University of Calgary, Canada
e-mail: roy@earth.geo.ucalgary.ca

Abstract

Cultural revival is one of the most sustainable ways in combating desertification. The citadel of Bam as one of the most important cultural and historical monuments is the largest and the oldest raw brick construction in the world.  No exact date of construction is reported, but the citadel seems to date back to 2000 years ago.  Bam citadel is located 193 km southeast Kerman city, Central Iran. The extent of the citadel is about 20 ha.  People lived in this citadel, but about 150 years ago the government had the people leave it in order to protect this historic monument.  The citadel of Bam was almost destroyed by the sever earthquake (6.3 on Richter scale with the duration of 12 seconds) on December 26th, 2003. Destruction of this historic monument revealed that it has been repeatedly destroyed and rebuilt. Due to the significance of Bam citadel in tourist industry of Iran, the present research was conducted.    Mineralogical, micromorphological and some physico-chemical properties were measured in the old raw bricks exposed by earthquake compared with the previously restored parts.  The results showed that among the investigated chemical properties electrical conductivity is quite different between the old exposed parts and the restored parts (6.4 dS/m and 42.4 dS/m respectively). Low crystalline smectite, illite and kaolinite were dominant clay minerals in all samples studied.  Massive microstructure with some gypsum crystals and igneous microlithes were observed in the thin sections under the study.  Some cellular structures were only found in old exposed walls of the citadel by SEM analysis. This may support the idea stated by archeologists that the dead bodies of human beings were buried between the bricks.  Some evidences of man made straw mats in the old bricks were also observed using SEM analysis. On the other hand, the dominant portion of bricks of restored parts was made of straw and mud.  After 2003 earthquake destruction, the citadel has been under restoration, so a good knowledge about the old raw bricks and the architecture of the exposed parts seems very essential for a better restoration.  It seems that soil science data about this huge monument can be as significant as archeological and anthropological studies.