The Supreme Court of India has recently instructed the Archaeological Survey of India (ASI) to implement a comprehensive, non-destructive investigation of the Gyanvapi mosque in Varanasi, Uttar Pradesh. This examination seeks to establish if the mosque was constructed on top of a temple.
The Purpose and Process of the Survey
The petitioners insist that the mosque was erected on the foundations of a Hindu temple and that the mosque contains concealed Hindu idols and structures. Responding to this argument, the court ordered ASI to form a five-member committee of experts to thoroughly examine the entire Gyanvapi compound. They are to utilize non-intrusive methods including ground-penetrating radar (GPR) and carbon dating techniques.
The purpose of this survey is to verify the existence of any remnants of a temple or any other Hindu structures within or beneath the mosque. The study will also seek to determine the age and origins of the existing structure. An observer has been appointed by the court to oversee the survey process and report any inconsistencies or infringements.
Non-Invasive Techniques in Archaeological Prospecting
Non-invasive methods come into play when an investigation requires entering a built structure where excavation is not allowed. These methods can be grouped into active and passive. Active methods involve injecting energy into the ground and measuring the response which gives an estimate of the ground’s material properties such as density, electrical resistance, and wave velocity.
Seismic techniques utilize shock waves to investigate subsurface structures while electromagnetic methods measure the electromagnetic responses after the injection of energy. Passive methods, on the other hand, revolve around measuring existing physical properties.
Tools Used in Non-Invasive Techniques
Various tools employed in these techniques include magnetometry, which detects magnetic anomalies caused by buried structures, and gravity surveying, which measures gravitational force variations due to subsurface features.
One of the primary tools to be used by ASI in this case; Ground-Penetrating Radar (GPR), operates by introducing a short radar impulse from a surface antenna. It records the time and magnitude of return signals from the subsoil.
Carbon dating, another vital tool, seeks to determine the age of organic material by measuring its carbon content.
Limitations of These Methods
Despite their use, these archaeological survey methods have limitations. The same physical properties of different materials can generate identical responses, creating ambiguity in identifying targets. The data collected is also often limited and contains measurement errors, making it challenging to accurately estimate the spatial distribution of properties. Furthermore, interpretations and decisions can be influenced by emotional and political factors especially in controversial cases involving religious sites.
About Archaeological Survey of India (ASI)
The ASI is a part of the Ministry of Culture and is the prime organization responsible for archaeological research and protection of the nation’s cultural heritage. It manages over 3650 ancient monuments, archaeological sites, and remains of national importance. Tasks performed by the ASI include conducting surveys of antiquarian remains, exploration, and excavation of archaeological sites, as well as conservation and maintenance of protected monuments. Founded in 1861 by Alexander Cunningham- the first Director-General of ASI, who is also known as the “Father of Indian Archaeology.”