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Mehdi Karimi Mansoob, Yaghub Mohammadifar,
year 3, Issue 9 (12-2019)
year 3, Issue 9 (12-2019)
Abstract
Abstract
The two most prominent types of material cultures in eastern Zagros are Bronze Age black burnished pottery (3rd millennium BC) and grey Iron Age pottery (second and first millennium BC) that were dog out during archaeological expeditions are being investigated and reconstructed. The technique of firing these two types of pottery will be analyzed in the present study. The main objective of this research was to reconstruct the similar conditions and techniques of these two pottery class using experimental archaeological methods and practical reconstruction of traditional kilns. Along this route, the technical similarities and differences are discussed, relying on archaeological data and comparing it with reconstructed samples. In this regard, two samples of each of the Bronze Age and Iron Age potteries were reconstructed and samples were produced and refurbished by traditional kiln that utilize modern laboratory facilities and precise temperature-measuring devices and are heated in the firing process. The results of the try and error tests indicated that baking with chemical reduction and emergence of gray color is the most important common feature of difference of gray pottery with other pottery assemblages. The firing technique and the structure of the kilns are the most important factors in distinguishing the two types of bronze age and iron age pottery assemblages. What is certain is that with the evolution of the furnace structure, the heat generated from about 700 ° C in the gray Yanniq period of the Bronze Age has increased to about 1000 ° C in the Iron Age specimens, resulting in a higher firing quality as well as a complete and complete chemical reduction of the vessels. Practical comparison of the reconstructed samples showed complete conformity of their characteristics with the ancient specimens (Pisa Tepe, Tushmalan Tepe and Ahmadabad Tepe) and also revealed the secret of producing these two species of gray pottery.
Keywords: Eastern Zagros Central Regions, Bronze Age Pottery, Iron Age Gray Pottery, Experimental Archeology, Kiln, Firing and Reduction.
Introduction
In modern archeology, the scientific question is not what we know, but how we know it. This point of view is one of the most important and at the same time the simplest modern archeological approach to past phenomena (Alizadeh, 2004: 91). Therefore, the idea of reconstructing the conditions and the environment in analogy with what was reported in the reports and data was presented. In response to such ambiguities, it can be said that using more modern methods in research such as “experimental archeology” will increase the accuracy of the premises. Early sections of this study have followed up on existing data and library studies of past sources and reports; therefore, in the next section, reconstructing the conditions and environment consistent with the information provided, has been the author’s main goal. In this section, the “kiln making” and the experience of firing the pottery in these kilns were practically achieved, leading to new information on the evolution of the gray pottery production; Proved the assumptions to be true, so that by producing products that were quite similar to ancient data, the key role of the resuscitation process in the firing process and the important role of kiln design and structure in the specific type of firing were demonstrated However, in some sources (Majidzadeh, 1370: 9-7), general references to the reasons for the pottery being grayed out as interfering with elements such as oxygen, iron, and carbon, and in other research, the reduction process was the main reason ( Kambakhshfard, 2010: 296). Finally, it can be added that according to the comparisons and studies of the samples, the firing of the Iron Age gray pottery somehow evolved into conscious firing methods during the first millennium BC. Although in the early Bronze Age achieved to somehow the technique of reduction firing, but only in Iron Age pottery assembladges, the correct pottery reduction firing can be clearly seen.
Discussion
After the pottery kiln reconstruction operation and the success of the production of the specimens, only by a very simple comparison, the accuracy of the existing probabilities, which were the unknowns of the equation, can be easily ascertained; however, accurate and scientific recordings of the work confirmed these results. Based on these empirical findings for the Bronze Age gray pottery, although previous findings indicate that the potter accessed the firing process may be regenerated, it is due to the amount of carbon accumulated in the samples (carbonization) that is due to its proximity to heavy smoke and firewood. It can be said it was still not possible to control precisely the firing conditions by the potters.
According to existing reports and objective observations of the Bronze Age pottery assemblages, such pottery has much thicker bodies than the gray Iron Age pottery, and empirical indications indicate lower firing temperatures; There are some other features that have been ignored because of their relevance to the subject of this study, that is, firing techniques. As for its firing technique, most of the existing documents refer to the possibility of a ditched type kilns, which is not far-fetched from the evidence.
Reconstruction of the firing conditions of the Bronze Age pottery indicated that the kiln was probably a small-size oven shaped hole that provided a relatively primitive chamber for controlling fire and firing in the vicinity of heavy smoke from firewood and fuel. Reconstructed furnace firing sector were able to provide similar conditions for oven-kilns. In this oven shape kiln, pottery was quite similar to the Bronze Age specimens, especially the Yaniqe or Godin IV pottery, but due to physical limitations and initial quality and reduction facilities, they were never comparable to those found in the Iron Age.
In fact, despite efforts to create optimum conditions, these types of kilns are not capable of achieving a higher quality product such as gray ceramics of the Iron Age, even though due to the excessive energy loss of the maximum heat produced in the oven by about 700 Centigrade did not exceed that production of higher quality pottery in these conditions is almost unlikely.
As the kiln construction techniques expands and evolves, the reconstituted kiln will eventually move closer to the plan of the kilns in the Iron Age, and after a complete overhaul, the result also confirms this claim. In this kiln, reasons such as the separation of the firing chamber, the dominance of proper flame allocation to the vessels, the closure of the pipes and the non-collision of the pipes with the air, made it easier to obtain the appropriate chemical reduction conditions.
In fact, the gray color of the potteries reconstituted with the conditions of the Iron Age kilns are mostly due to the correct reduction and dependence of the carbon chemical interactions and the consumption and replacement of the oxygen present in the composite iron oxide in the ceramic body soil. The technical differences in these two species, which are mainly due to differences in the structure of the kiln structure, are evident in the firing quality of the bodies and the difference in the intensity of carbon accumulation and the color difference between the surface and the body depth.
Conclusion
After examining the documentation available in the time and location of interested research subject, it can be said that the gray pottery has two major variations, both of which have significant differences in terms of time of occurrence, originating culture, and specific production and reduction techniques. In terms of firing technique characteristics, it can be said that the only similarity between these two cultural products is the presence of a “different gray color” in the body of both types of pottery, which has brought them closer together because of the differences in the characteristics of the other species.
The characteristics of the Early Bronze Age gray pottery that distinguishes it from the Iron Age gray pottery lie in the presence of two main factors, namely the type of kilns and the pottery body features. According to the comparison and examination of samples, firing gray pottery assembladges of the Iron Age somehow evolves conscious firing methods and only in the examples of the Iron Age pottery can a complete and correct chemical reduction of a pottery be clearly seen.
In fact, both of these types of potteries are common in creating an atmosphere of chemical reduction in firing, both of which are interesting in their quality and type of performance, which can be attributed to the progressive evolution of the kiln structure and the facilities and knowledge necessary for its construction and observance for centuries.
The two most prominent types of material cultures in eastern Zagros are Bronze Age black burnished pottery (3rd millennium BC) and grey Iron Age pottery (second and first millennium BC) that were dog out during archaeological expeditions are being investigated and reconstructed. The technique of firing these two types of pottery will be analyzed in the present study. The main objective of this research was to reconstruct the similar conditions and techniques of these two pottery class using experimental archaeological methods and practical reconstruction of traditional kilns. Along this route, the technical similarities and differences are discussed, relying on archaeological data and comparing it with reconstructed samples. In this regard, two samples of each of the Bronze Age and Iron Age potteries were reconstructed and samples were produced and refurbished by traditional kiln that utilize modern laboratory facilities and precise temperature-measuring devices and are heated in the firing process. The results of the try and error tests indicated that baking with chemical reduction and emergence of gray color is the most important common feature of difference of gray pottery with other pottery assemblages. The firing technique and the structure of the kilns are the most important factors in distinguishing the two types of bronze age and iron age pottery assemblages. What is certain is that with the evolution of the furnace structure, the heat generated from about 700 ° C in the gray Yanniq period of the Bronze Age has increased to about 1000 ° C in the Iron Age specimens, resulting in a higher firing quality as well as a complete and complete chemical reduction of the vessels. Practical comparison of the reconstructed samples showed complete conformity of their characteristics with the ancient specimens (Pisa Tepe, Tushmalan Tepe and Ahmadabad Tepe) and also revealed the secret of producing these two species of gray pottery.
Keywords: Eastern Zagros Central Regions, Bronze Age Pottery, Iron Age Gray Pottery, Experimental Archeology, Kiln, Firing and Reduction.
Introduction
In modern archeology, the scientific question is not what we know, but how we know it. This point of view is one of the most important and at the same time the simplest modern archeological approach to past phenomena (Alizadeh, 2004: 91). Therefore, the idea of reconstructing the conditions and the environment in analogy with what was reported in the reports and data was presented. In response to such ambiguities, it can be said that using more modern methods in research such as “experimental archeology” will increase the accuracy of the premises. Early sections of this study have followed up on existing data and library studies of past sources and reports; therefore, in the next section, reconstructing the conditions and environment consistent with the information provided, has been the author’s main goal. In this section, the “kiln making” and the experience of firing the pottery in these kilns were practically achieved, leading to new information on the evolution of the gray pottery production; Proved the assumptions to be true, so that by producing products that were quite similar to ancient data, the key role of the resuscitation process in the firing process and the important role of kiln design and structure in the specific type of firing were demonstrated However, in some sources (Majidzadeh, 1370: 9-7), general references to the reasons for the pottery being grayed out as interfering with elements such as oxygen, iron, and carbon, and in other research, the reduction process was the main reason ( Kambakhshfard, 2010: 296). Finally, it can be added that according to the comparisons and studies of the samples, the firing of the Iron Age gray pottery somehow evolved into conscious firing methods during the first millennium BC. Although in the early Bronze Age achieved to somehow the technique of reduction firing, but only in Iron Age pottery assembladges, the correct pottery reduction firing can be clearly seen.
Discussion
After the pottery kiln reconstruction operation and the success of the production of the specimens, only by a very simple comparison, the accuracy of the existing probabilities, which were the unknowns of the equation, can be easily ascertained; however, accurate and scientific recordings of the work confirmed these results. Based on these empirical findings for the Bronze Age gray pottery, although previous findings indicate that the potter accessed the firing process may be regenerated, it is due to the amount of carbon accumulated in the samples (carbonization) that is due to its proximity to heavy smoke and firewood. It can be said it was still not possible to control precisely the firing conditions by the potters.
According to existing reports and objective observations of the Bronze Age pottery assemblages, such pottery has much thicker bodies than the gray Iron Age pottery, and empirical indications indicate lower firing temperatures; There are some other features that have been ignored because of their relevance to the subject of this study, that is, firing techniques. As for its firing technique, most of the existing documents refer to the possibility of a ditched type kilns, which is not far-fetched from the evidence.
Reconstruction of the firing conditions of the Bronze Age pottery indicated that the kiln was probably a small-size oven shaped hole that provided a relatively primitive chamber for controlling fire and firing in the vicinity of heavy smoke from firewood and fuel. Reconstructed furnace firing sector were able to provide similar conditions for oven-kilns. In this oven shape kiln, pottery was quite similar to the Bronze Age specimens, especially the Yaniqe or Godin IV pottery, but due to physical limitations and initial quality and reduction facilities, they were never comparable to those found in the Iron Age.
In fact, despite efforts to create optimum conditions, these types of kilns are not capable of achieving a higher quality product such as gray ceramics of the Iron Age, even though due to the excessive energy loss of the maximum heat produced in the oven by about 700 Centigrade did not exceed that production of higher quality pottery in these conditions is almost unlikely.
As the kiln construction techniques expands and evolves, the reconstituted kiln will eventually move closer to the plan of the kilns in the Iron Age, and after a complete overhaul, the result also confirms this claim. In this kiln, reasons such as the separation of the firing chamber, the dominance of proper flame allocation to the vessels, the closure of the pipes and the non-collision of the pipes with the air, made it easier to obtain the appropriate chemical reduction conditions.
In fact, the gray color of the potteries reconstituted with the conditions of the Iron Age kilns are mostly due to the correct reduction and dependence of the carbon chemical interactions and the consumption and replacement of the oxygen present in the composite iron oxide in the ceramic body soil. The technical differences in these two species, which are mainly due to differences in the structure of the kiln structure, are evident in the firing quality of the bodies and the difference in the intensity of carbon accumulation and the color difference between the surface and the body depth.
Conclusion
After examining the documentation available in the time and location of interested research subject, it can be said that the gray pottery has two major variations, both of which have significant differences in terms of time of occurrence, originating culture, and specific production and reduction techniques. In terms of firing technique characteristics, it can be said that the only similarity between these two cultural products is the presence of a “different gray color” in the body of both types of pottery, which has brought them closer together because of the differences in the characteristics of the other species.
The characteristics of the Early Bronze Age gray pottery that distinguishes it from the Iron Age gray pottery lie in the presence of two main factors, namely the type of kilns and the pottery body features. According to the comparison and examination of samples, firing gray pottery assembladges of the Iron Age somehow evolves conscious firing methods and only in the examples of the Iron Age pottery can a complete and correct chemical reduction of a pottery be clearly seen.
In fact, both of these types of potteries are common in creating an atmosphere of chemical reduction in firing, both of which are interesting in their quality and type of performance, which can be attributed to the progressive evolution of the kiln structure and the facilities and knowledge necessary for its construction and observance for centuries.
Dr Yousef Moradi,
year 7, Issue 25 (12-2023)
year 7, Issue 25 (12-2023)
Abstract
Abstract
The Bisotun bridge was built across the Dinavar Ab River, flowing on the eastern outskirts of the present-day town of Bisotun. The construction of the bridge’s substructure was initiated in the late Sasanian period, but the program was abruptly terminated, as is the case with other Sasanian projects in Bisotun. Subsequently, the Ḥasanwayhids, a local Kurdish dynasty in western Iran, completed the construction of the bridge. High traffic and natural hazards such as floods and earthquakes have inflicted damage upon the bridge in subsequent periods, i.e., from the Saljuq era to the first Pahlavi period. Consequently, governments made considerable efforts to restore or reconstruct various parts of the bridge. Workshops were established at a short distance northeast of the bridge to provide construction materials for the restoration and reconstruction of the damaged parts. To the northeast of the bridge, there exists a low mound measuring 50 m in length and 40 m in width. The mound was excavated in 2002 under the direction of the present author, revealing four distinct archaeological strata. The earliest layer (I) includes a seasonal settlement from the Qajar period. Layer II contains a cemetery from the same period. Layer III encompasses several brick and lime kilns, dating back to the Ilkhanid and Qajar periods. Layer IV yielded parts of a stone-cutting workshop from the late Sasanian/ Ḥasanwayhid period. This article aims to provide the first comprehensive description of the findings within each archaeological stratum, using historical and descriptive-analytical research methods. We will also propose a chronological framework for the excavated materials based on archaeological evidence and thermoluminescence dating analysis. Furthermore, the article will delve into the production processes of brick and lime produced in the excavated kilns. Moreover, we will provide insights into the process by which the stone blocks were produced in the stone-cutting workshop.
Keywords: Bisotun Bridge, Stone Workshop, Brick, Lime, Kiln, Cemetery.
Introduction
The Bisotun Bridge is located on the eastern outskirts of the present-day town of Bisotun, on the “Great Khorasan” highway to Baghdad, spanning the Dinavar Ab River (Fig. 1). The bridge is 145 m long and consists of six spans. The bridge piers are constructed of well-dressed stone blocks, while the walls, buttresses, and vaults are made of bricks. Archaeological excavations and architectural studies have revealed that the bridge has been constructed, reconstructed, and repaired in eight distinct stages, occurring at different times ranging from the late Sasanian period to the first Pahlavi era.
On the northeast side of the bridge, there was a low-laying mound measuring 50 m in length and 40 m in width (Figs. 2–3). This mound was covered with a considerable amount of kiln slag, fragments of baked bricks in various sizes, and stone blocks. These findings indicated the presence of workshops related to the production of building materials for the initial construction and/or repair of the bridge. In 2002, the mound was partially excavated under the direction of the present author. The archaeological deposits of the mound had an approximate thickness of 3.50 m. The excavation was carried out with two objectives. First, to identify the potential workshops involved in the production of building materials used in the construction of the bridge. Second, to shed light on the processes by which the building materials were produced in these workshops.
This article aims to first provide a detailed description of the findings from each archaeological stratum, employing historical and descriptive-analytical research methods. Subsequently, by utilizing archaeological evidence and thermoluminescence dating analysis, we will determine the dates of the architectural structures under investigation. Furthermore, we will endeavor to explain the processes and techniques employed in the production of brick and lime production based on the layout and architectural characteristics of each kiln. Moreover, we will discuss the process by which finely cut stone blocks were produced in the stone-cutting workshop. We intend to address the following questions, drawing on historical documents and archaeological evidence:
1. During which period were the excavated workshops actively in operation?
2. What were the production processes of building materials in these workshops?
3. Can we establish a chronological framework for the excavated cemetery?
4. Are the graves associated with one religious group, or do different groups of graves represent diverse religious affiliations?
The site
During the excavation of the mound, a stone-cutting workshop from the late Sasanian or Hasanwayhid period was discovered. In this workshop, stone blocks for the construction of the bridge piers were skillfully dressed (Fig. 4). The workshop suffered damage due to the subsequent construction of brick and lime kilns (Figs. 5, 7, and 17). Nonethless, twelve cut stone blocks of varying sizes and shapes were found in the excavated area. Furthermore, the excavation revealed three kilns (Figs. 5-6) engaged in the production of bricks and lime.
Kiln 1
This kiln is oriented in a north-south direction, and only its furnace has survived. The furnace represents three construction phases. In Phase I, it had a rectangular plan with external dimensions of 7.50 m in length and 4.80 m in width (Figs. 7–8). The relatively modest size of the furnace indicates that it was likely not intended for extensive brick production but rather for the supply of bricks for the reconstruction and repair of the bridge during the Ilkhanid period. In Phase II, the furnace’s plan turned to a circular shape, with a diameter of 3.30 m and a height of 2.10 m (Figs. 7 and 16). In Phase III, another air flue was built upon the one from Phase II. During Phases II and III, this kiln was used for lime production. Originally functioned as a brick-manufacturing kiln during the Ilkhanid period, it was transformed into a lime kiln in the Qajar period.
Kiln 2
This kiln has an approximately circular plan (Figs. 17–18). The inner diameter of the kiln ranges from 2.50 to 2.60 m, while the remaining height of its walls stands at 3.30 m (Figs. 19–21). Within the kiln, there is a channel oriented in a north-south direction, allowing the inflow of air for the combustion of fire inside the kiln. The presence of substantial quantities of lime inside the kiln strongly suggests its use in the production of lime for the repair of bridge piers.
Kiln 3
This kiln has a circular plan with a varying inner diameter. The kiln’s dimensions include a diameter of 1.80 m from the floor up to a height of 55 cm, a diameter of 2.40 m from there to a height of 1.20 m, and a diameter of 2.70 m from that point to the highest part of the wall (Figs. 24–27). The channel on the floor of the kiln is designed to facilitate air circulation. Three additional channels, sharing similar characteristics, have been built on top of this primary channel. Similar to kiln 2, the presence of substantial quantities of lime inside the kiln indicates that it was used to produce lime for the repair of bridge piers.
Conclusion
The excavation of the mound has yielded four distinct archaeological strata. Layer I represents a seasonal nomadic settlement dating back to the Qajar period. Layer II consists of a graveyard from the Qajar period. Layer III contains three kilns used for brickmaking and lime production, which can be dated back to the Ilkhanid and Qajar periods. Layer IV reveals a stone-cutting workshop, likely dating back to the Sasanian or Ḥasanwayhid period. The proximity of these kilns and the stone-cutting workshop to the bridge indicates that these workshops were established nearby to facilitate the construction process and ensure a readily available supply of building materials.
The brick-manufacturing kiln discovered in the excavation is an extensive open kiln with fixed bricks and a stationary fire. It appears to lack an upper chamber or enclosed walls. In this kiln, the brick-making process involved stacking mud bricks on top of the kiln’s furnace to form cylindrical, square, or polygonal brick towers. These bricks were arranged with gaps between them to allow for the circulation of air, hot gases, and flames. Openings in the lower rows connected to the kiln’s fire vents, facilitating heat transfer. After the initial firing, the baked bricks were removed, and fresh bricks were placed for the next firing. The design and operation of this kiln closely resemble those from the Sasanian period, suggesting little change in brick production technology over time.
The lime kilns are of the pit type with a circular layout. These kilns relied on limestone and a fixed fire, resulting in uneven temperature distribution and variable lime quality. Often, stones remained either uncalcined or partially burned. Lime production involved two methods: arranging limestone around the kiln’s circumference, with heat generated in the central empty space, or stacking alternating layers of charcoal and limestone inside the kiln. The top of the kiln was sealed with mud mortar. These kilns were used during the Qajar period to produce lime for bridge pier repairs.
Within the stone-cutting workshop, stone blocks were meticulously shaped for use in constructing bridge piers. Initially, stone cutters extracted stones from the quarry and cut them into geometric shapes and approximate sizes. Subsequently, the blocks were transported to the workshop, where they underwent further cutting, shaping, and surface polishing. One block bears a stone-cutting mark on its smooth surface, indicating that these stone-cutting marks were made in the workshop.
Acknowledgments
I am indebted to the Iranian Centre for Archaeological Research (ICAR) for generously granting the excavation permits, and to the Bisotun World Heritage Base for its financial support, unfailing administrative cooperation, and logistical assistance.
I would also like to express my sincere appreciation to the following individuals for their invaluable contributions. Zeinab Valizadeh for proofreading the text; Hamed Rezae for producing the architectural plans and cross sections; Sara Mahbobi for redrawing and revising the plans and cross sections; Dariush Afkari for supplying the countor map of the site; and Elham Afkari for her photography of the coin and seal.
Conflict of Interest
No potential conflict of interest was reported by the Author(s).
The Bisotun bridge was built across the Dinavar Ab River, flowing on the eastern outskirts of the present-day town of Bisotun. The construction of the bridge’s substructure was initiated in the late Sasanian period, but the program was abruptly terminated, as is the case with other Sasanian projects in Bisotun. Subsequently, the Ḥasanwayhids, a local Kurdish dynasty in western Iran, completed the construction of the bridge. High traffic and natural hazards such as floods and earthquakes have inflicted damage upon the bridge in subsequent periods, i.e., from the Saljuq era to the first Pahlavi period. Consequently, governments made considerable efforts to restore or reconstruct various parts of the bridge. Workshops were established at a short distance northeast of the bridge to provide construction materials for the restoration and reconstruction of the damaged parts. To the northeast of the bridge, there exists a low mound measuring 50 m in length and 40 m in width. The mound was excavated in 2002 under the direction of the present author, revealing four distinct archaeological strata. The earliest layer (I) includes a seasonal settlement from the Qajar period. Layer II contains a cemetery from the same period. Layer III encompasses several brick and lime kilns, dating back to the Ilkhanid and Qajar periods. Layer IV yielded parts of a stone-cutting workshop from the late Sasanian/ Ḥasanwayhid period. This article aims to provide the first comprehensive description of the findings within each archaeological stratum, using historical and descriptive-analytical research methods. We will also propose a chronological framework for the excavated materials based on archaeological evidence and thermoluminescence dating analysis. Furthermore, the article will delve into the production processes of brick and lime produced in the excavated kilns. Moreover, we will provide insights into the process by which the stone blocks were produced in the stone-cutting workshop.
Keywords: Bisotun Bridge, Stone Workshop, Brick, Lime, Kiln, Cemetery.
Introduction
The Bisotun Bridge is located on the eastern outskirts of the present-day town of Bisotun, on the “Great Khorasan” highway to Baghdad, spanning the Dinavar Ab River (Fig. 1). The bridge is 145 m long and consists of six spans. The bridge piers are constructed of well-dressed stone blocks, while the walls, buttresses, and vaults are made of bricks. Archaeological excavations and architectural studies have revealed that the bridge has been constructed, reconstructed, and repaired in eight distinct stages, occurring at different times ranging from the late Sasanian period to the first Pahlavi era.
On the northeast side of the bridge, there was a low-laying mound measuring 50 m in length and 40 m in width (Figs. 2–3). This mound was covered with a considerable amount of kiln slag, fragments of baked bricks in various sizes, and stone blocks. These findings indicated the presence of workshops related to the production of building materials for the initial construction and/or repair of the bridge. In 2002, the mound was partially excavated under the direction of the present author. The archaeological deposits of the mound had an approximate thickness of 3.50 m. The excavation was carried out with two objectives. First, to identify the potential workshops involved in the production of building materials used in the construction of the bridge. Second, to shed light on the processes by which the building materials were produced in these workshops.
This article aims to first provide a detailed description of the findings from each archaeological stratum, employing historical and descriptive-analytical research methods. Subsequently, by utilizing archaeological evidence and thermoluminescence dating analysis, we will determine the dates of the architectural structures under investigation. Furthermore, we will endeavor to explain the processes and techniques employed in the production of brick and lime production based on the layout and architectural characteristics of each kiln. Moreover, we will discuss the process by which finely cut stone blocks were produced in the stone-cutting workshop. We intend to address the following questions, drawing on historical documents and archaeological evidence:
1. During which period were the excavated workshops actively in operation?
2. What were the production processes of building materials in these workshops?
3. Can we establish a chronological framework for the excavated cemetery?
4. Are the graves associated with one religious group, or do different groups of graves represent diverse religious affiliations?
The site
During the excavation of the mound, a stone-cutting workshop from the late Sasanian or Hasanwayhid period was discovered. In this workshop, stone blocks for the construction of the bridge piers were skillfully dressed (Fig. 4). The workshop suffered damage due to the subsequent construction of brick and lime kilns (Figs. 5, 7, and 17). Nonethless, twelve cut stone blocks of varying sizes and shapes were found in the excavated area. Furthermore, the excavation revealed three kilns (Figs. 5-6) engaged in the production of bricks and lime.
Kiln 1
This kiln is oriented in a north-south direction, and only its furnace has survived. The furnace represents three construction phases. In Phase I, it had a rectangular plan with external dimensions of 7.50 m in length and 4.80 m in width (Figs. 7–8). The relatively modest size of the furnace indicates that it was likely not intended for extensive brick production but rather for the supply of bricks for the reconstruction and repair of the bridge during the Ilkhanid period. In Phase II, the furnace’s plan turned to a circular shape, with a diameter of 3.30 m and a height of 2.10 m (Figs. 7 and 16). In Phase III, another air flue was built upon the one from Phase II. During Phases II and III, this kiln was used for lime production. Originally functioned as a brick-manufacturing kiln during the Ilkhanid period, it was transformed into a lime kiln in the Qajar period.
Kiln 2
This kiln has an approximately circular plan (Figs. 17–18). The inner diameter of the kiln ranges from 2.50 to 2.60 m, while the remaining height of its walls stands at 3.30 m (Figs. 19–21). Within the kiln, there is a channel oriented in a north-south direction, allowing the inflow of air for the combustion of fire inside the kiln. The presence of substantial quantities of lime inside the kiln strongly suggests its use in the production of lime for the repair of bridge piers.
Kiln 3
This kiln has a circular plan with a varying inner diameter. The kiln’s dimensions include a diameter of 1.80 m from the floor up to a height of 55 cm, a diameter of 2.40 m from there to a height of 1.20 m, and a diameter of 2.70 m from that point to the highest part of the wall (Figs. 24–27). The channel on the floor of the kiln is designed to facilitate air circulation. Three additional channels, sharing similar characteristics, have been built on top of this primary channel. Similar to kiln 2, the presence of substantial quantities of lime inside the kiln indicates that it was used to produce lime for the repair of bridge piers.
Conclusion
The excavation of the mound has yielded four distinct archaeological strata. Layer I represents a seasonal nomadic settlement dating back to the Qajar period. Layer II consists of a graveyard from the Qajar period. Layer III contains three kilns used for brickmaking and lime production, which can be dated back to the Ilkhanid and Qajar periods. Layer IV reveals a stone-cutting workshop, likely dating back to the Sasanian or Ḥasanwayhid period. The proximity of these kilns and the stone-cutting workshop to the bridge indicates that these workshops were established nearby to facilitate the construction process and ensure a readily available supply of building materials.
The brick-manufacturing kiln discovered in the excavation is an extensive open kiln with fixed bricks and a stationary fire. It appears to lack an upper chamber or enclosed walls. In this kiln, the brick-making process involved stacking mud bricks on top of the kiln’s furnace to form cylindrical, square, or polygonal brick towers. These bricks were arranged with gaps between them to allow for the circulation of air, hot gases, and flames. Openings in the lower rows connected to the kiln’s fire vents, facilitating heat transfer. After the initial firing, the baked bricks were removed, and fresh bricks were placed for the next firing. The design and operation of this kiln closely resemble those from the Sasanian period, suggesting little change in brick production technology over time.
The lime kilns are of the pit type with a circular layout. These kilns relied on limestone and a fixed fire, resulting in uneven temperature distribution and variable lime quality. Often, stones remained either uncalcined or partially burned. Lime production involved two methods: arranging limestone around the kiln’s circumference, with heat generated in the central empty space, or stacking alternating layers of charcoal and limestone inside the kiln. The top of the kiln was sealed with mud mortar. These kilns were used during the Qajar period to produce lime for bridge pier repairs.
Within the stone-cutting workshop, stone blocks were meticulously shaped for use in constructing bridge piers. Initially, stone cutters extracted stones from the quarry and cut them into geometric shapes and approximate sizes. Subsequently, the blocks were transported to the workshop, where they underwent further cutting, shaping, and surface polishing. One block bears a stone-cutting mark on its smooth surface, indicating that these stone-cutting marks were made in the workshop.
Acknowledgments
I am indebted to the Iranian Centre for Archaeological Research (ICAR) for generously granting the excavation permits, and to the Bisotun World Heritage Base for its financial support, unfailing administrative cooperation, and logistical assistance.
I would also like to express my sincere appreciation to the following individuals for their invaluable contributions. Zeinab Valizadeh for proofreading the text; Hamed Rezae for producing the architectural plans and cross sections; Sara Mahbobi for redrawing and revising the plans and cross sections; Dariush Afkari for supplying the countor map of the site; and Elham Afkari for her photography of the coin and seal.
Conflict of Interest
No potential conflict of interest was reported by the Author(s).
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