Allahabad High Court’s May 12 order to conduct a “scientific survey” — which the Supreme Court has deferred — to establish the age, nature, etc, of the ‘shivling’ found within the precincts of the Gyanvapi mosque complex has raised a flurry of questions about how this will be done. TOI’s Swati Mathur spoke to Chandra Mohan Nautiyal, former scientist-in-charge of the Radiocarbon Lab at Lucknow’s Birbal Sahni Institute of Palaeosciences and one of India’s best-known experts in radiocarbon dating, to understand the processes and the possibilities that lie ahead.
Is it correct that the court’s order to conduct a scientific survey of the Gyanvapi complex will involve carbon dating of the ‘shivling’? What does this process involve?
The scientific survey of a site such as this can be done in many ways – chemical analyses, detecting underground structures by ground penetrating radar (GPR), or by establishing the site’s age, which is referred to as ‘dating’ it.
Dating can be done in a dozen different ways, including radiocarbon dating, depending upon the material. I think the method will eventually be decided by the Archaeological Survey of India or some team of experts. Ultimately, the aim, as I understand it, is to determine when the ‘shivling’ was installed inside the Gyanvapi precincts, which is different from the age of the stone with which it was built. The stone can be millions or even billions of years old. Several questions, such as whether this ‘shivling’ acquired its shape naturally or if it was shaped, will also have to be considered.
What is carbon dating and can it be done at the Gyanvapi mosque complex?
Carbon dating is a widely used tool to establish the age of organic materials that were once living, such as plants and animals. The presence of radiocarbon can typically be traced back to about 40,000 to 50,000 years. If the rock is older, there would be no radiocarbon left.
Even if radiocarbon accumulated in sedimentary rock, to measure it one would need to extract some portion of the rock. One has to see if it will be allowed since extraction from the ‘shivling’ may be considered its ‘khandan’ (breaking). Tackling such problems needs creative thinking and new approaches may have to be devised. So, a project to ascertain when the ‘shivling’ was installed there may have to be taken up as a research problem involving trial and error.
From the radiocarbon angle, one will have to look for the remains of flowers, leaves or fruit that may have been offered to the ‘shivling’, and are buried near the place where the ‘shivling’ has been found. The odds are not good though. This would help establish a limit on the approximate time when people would have started worshipping at the site.
If, however, some extraction from the rock is permitted, the sample may be sent to some accelerated mass spectrometry (AMS) laboratory. In India, at present, we have these facilities at Inter-University Accelerator Centre (IUAC) in Delhi and the Physical Research Laboratory (PRL) in Ahmedabad. This, however, will still not establish when the ‘shivling’ was installed at the site.
A third possibility from the radiocarbon dating point of view is if samples of wood are found from the site – from a door, for instance – which can help ascertain when the tree was felled for making the door. Again, one would work on the assumption that if a temple was built around a naturally occurring ‘shivling’, the doors would have been installed after the ‘shivling’ began to be worshipped. The ‘shivling’ may also have been established after making the temple.
What are the other ways in which such a site may be studied?
The other ways to study the site include a study of the structure under the ‘shivling’ through a ground penetrating radar, or analysing sediment through methods like thermoluminescence dating (TL) or optically stimulated luminescence dating (OSL), both of which can ascertain the duration of time for which the soil beneath the surface has not been exposed to light or subjected to heat. But again, these have to be tried and will not definitely provide answers. That is why I termed it research.
How long does the process of radiocarbon dating typically take?
The time taken will also depend on how soon the suitable samples are made available. Using the AMS method, an extracted sample will be converted into graphite and the measurements made, which may take about a week after tuning the equipment.
A technique best used for plant and animal remains, not stones like this
Mohita.Tewari@timesgroup.com
The discovery of a ‘shivling-like’ structure inside Varanasi’s Gyanvapi mosque complex, in May last year, triggered a debate about its age. Many believe it is a ‘shivling’ while others claim it is part of a fountain in the mosque’s ‘wuzu khana’ (ablution pond). Hindus, who had been demanding the right to pray at the Shringar Gauri shrine in the mosque’s outer wall, first sought carbon dating of the purported shivling, and more recently of the entire Gyanvapi complex, to ascertain the age and nature of the structure.
On May 12, the Allahabad high court had allowed a scientific survey of the ‘shivling’ to determine its age, but the Supreme Court on Friday deferred the survey. The HC had also directed the authorities to ensure the structure wasn’t harmed. Although the HC didn’t specify a technique, carbon dating has been the most widely used method in such cases. TOI explains what carbon dating is, and whether it can help ascertain the age of the ‘shivling’.
A Reliable Age Scale
“It is a method of calculating the age of objects up to about 50,000 years old by measuring the amount of radioactive carbon (C-14), commonly called as radiocarbon, in them,” says Chandra Mohan Nautiyal, a retired scientist who was part of many archaeological dating projects and was in the department that dated material from the Ayodhya temple excavation when he worked at Lucknow’s Birbal Sahni Institute of Palaeosciences (BSIP).
“Basically, it is a technique used to determine the approximate age of materials like wood, foodgrain, leather, and sediments like some stones, among others,” he adds.
The carbon that plants receive from the atmosphere contains traces of radiocarbon. As BSIP scientist Sanjay Kumar Singh Gahlaud explains:
“C-14 is constantly being created in the earth’s atmosphere by the interaction of cosmic rays with atmospheric nitrogen. The generated C-14 combines with atmospheric oxygen to form radioactive carbon dioxide, which is utilised by plants for photosynthesis.”
When an animal eats plants, radiocarbon enters its body. When carnivores prey on plant-eating animals, radiocarbon enters their bodies, says Nautiyal.
Less C-14 Means More Years
When plants die, they stop assimilating C-14, even as the amount they have accumulated continues to decay. “After a plant or animal dies, radiocarbon in it begins to decrease as it undergoes radioactive decay,” says Gahlaud. The decay rate is expressed in ‘half-life’ – the time in which radioactivity of a specimen reduces by half. C-14 has a half-life of 5,730 years.
Scientists estimate the age of dead plant or animal matter by counting the C-14 isotope present in it. Such material dispersed in soil allows dating of that soil also. Using this method, one can not only compare the dates of events that occurred long intervals apart but also “find precise and accurate dates. For example, using this method, scientists can pinpoint the end of the last ice age,” says Nautiyal.
