For villagers of Bori Budruk, the geological term “tephra” is a local legend. The village, around 100-km from Pune city, is nestled along the banks of the Kukadi river. With a population of around 6,000, the villagers are all well versed with the technicalities of the geological term – tephra – the dust-sized particles from a supervolcanic eruption that travels long distances in the atmosphere and settles over time into a sediment layer.

In this case, the sediment has made a journey of 3,000 km all the way from a Sumatran volcano Toba and settled in Maharashtra, indicates research. Well known among geologists world over, the Toba volcano was once dreaded, for having produced three massive eruptions that led to near mass extinction-like conditions with thick ash travelling all the way to Asia, Africa as well as Europe.

These three eruptions are said to have taken place 800,000 years, 500,000 years and 75,000 years ago. The tephra in Bori, therefore, is a heritage site like no other.

The geological phenomenon is located alongside the Kukadi river which is the main source for water for domestic purposes in the village. Along one of the banks, also lies a smashan ghat (cemetery). Researchers from all over the world visit the Kukadi river bank for samples of tephra – which has now become the identity of Bori Budruk.

Bori Budruk’s villagers are currently struggling to protect this tephra. At the forefront of this battle, is the couple Pushpa and Amol Korde. Pushpa has been the sarpanch for ten years now.

“When we first came to know about the tephra, we felt responsible for conserving it,” Amol told Mongabay-India. “This is something rare, and it is part of our village and our identity. People from all over the world come here and collect samples. We felt an urgent need to protect, and conserve this eco-heritage.”

Amol even went on to enroll for a postgraduate diploma in heritage conservation from Pune’s Deccan College. “I wanted to get a complete understanding of the terminology,” he said. “This would also help me spread awareness among the other villagers.”

Two families closest to the site have been assigned the responsibility of maintaining a register to keep track of all those who come and go with samples.

Pushpa Korde, the village head of Bori Budruk, along with her husband and other villagers have been implementing plans to protect their village river bed that has become a site of geological importance. Photo credit: Manjula Nair

“We recently had scientists from Israel who were interested,” said Amol. “We had school children coming in right before Covid-19 hit.”

However, the biggest victory for the villagers was stopping a sand mining challenge in 2016. Pushpa explained, “This was a big win for us all. There was rampant sand mining in the area, and a lot of the tephra was being scooped out since 2012.”

“We took the matter to the high court, which directed the collector to stop the work in 2016,” said Pushpa. “Now, we feel more of a need to protect this site.”

With plans to develop a site museum, and a five-village cluster eco-tourism trail, the local community has big plans for the site. “Our biggest problem is government funding,” she said. “We keep pushing for the same, but since it is a village our voices often go unheard. We are worried that the tephra may not stand the test of time, as the river washes away the sediments every year. Compared to how it used to be earlier, the tephra is now concentrated in patches.”

The villagers have also formed a 15-member heritage conservation committee that regularly holds meetings with state officials. Thanks to consistent efforts, the panel signed a memorandum of understanding with the Deccan College in Pune in June 2020, to jointly preserve the site.

Architects in the village have also drawn up blueprints and designs as to what the site museum could look like, with the tephra encased in glass boxes. However, there is still worry about the future.

A significant discovery

The Toba supervolcanic eruptions spewed ash that settled into tephra and tuff. Unlike tephra, tuff is porous. Imagine a spongy-looking rock, formed from volcanic ash. This, in turn, has been classified into three types according to the three eruption timelines: oldest Toba tuff, middle Toba tuff and the youngest Toba tuff. Of these, the youngest Toba tuff has been studied closely, with scientists tracing genetic bottlenecks, which meant a significant decrease in human population affecting the evolution of mankind.

The tephra at Bori, however, is the subject of a deeply contentious scientific debate.

Way back in December 1986, Sharad Rajguru, professor and now a retired head of the department of archaeology from Pune’s Deccan College, was part of one of the first research teams that stumbled upon the ash.

“The site was first discovered by another researcher and professor Vishwas Kale,” Rajguru said. “He is a geomorphologist and found lower Paleolithic stone tools at the site. Later, I arrived there with a group of about four research members.”

“One of my students who was with us accidentally struck some whitish material that coated the riverbanks,” he said. “We brought it back with us to Deccan College and examined it under a microscope. The same night, it was confirmed that this is volcanic ash.”

Rajguru remembers how his team members celebrated over drinks that night. “This was a very surprising discovery for all of us,” he said. “We were so happy to have found something of this magnitude!”

Bori Budruk village, around 100-km from Pune city, is nestled along the banks of the Kukadi river. Map from Datawrapper

It was towards the end of the 80s, when the villagers saw a young researcher Sheila Mishra who was Rajguru’s student rummaging along the riverbed to collect samples of the tephra. To aid her research, Mishra even rented a room at Bori Budruk. Seeing Mishra elicited the villagers’ curiosity. “They would often ask me what I am doing,” Mishra recounts. “I would try and explain as much as I could.”

However, little did the villagers know, Mishra’s work would transform their village into a geoarchaeologists’ hub. It was after she published her research paper in the scientific journal Current Science that the villagers came to know of the significance.

Dilip Pawar, 58, still remembers the time Mishra frequented his hotel in the village for her meals. “I was her point of contact,” he laughed. “If there were any researchers who wanted to study the tephra, she would send them along to me. I would accompany them to the riverbanks, and show them around.”

“When she first came here, we had no idea that this ‘sand’ that we see every day was so important,” Pawar said. “Now, everyone in Bori Budruk is proud to be associated with this kind of heritage.”

Mishra’s arrival, however, served another purpose, more so in a geological sense. Her visits entailed a scientific deep dive into the actual dating of the tephra. “I was interested in the dating,” she said. “You see, the site first came into focus when Dr Kale first discovered these Aeshculian tools that date back to the lower Paleolithic era. It is very difficult to date these tools in India. However, volcanic ash can be dated. So that’s how I got interested.”

A piece of tephra from the Kukadi riverbed. Discovered first in the 80s by researchers, the material has become the identity of Bori Budruk. Photo credit: Manjula Nair

Describing her travels to Bori Budruk, Mishra said, “Since I had to spend a lot of time there, I decided to rent a room.”

Mishra worked tirelessly over the next couple of years. She covered the stretch of the riverbank to understand the site’s stratigraphy, a branch of geology concerned with the study of rock layers and layering.

After sending the samples for dating, the tephra turned out to be from the oldest Toba tuff era. “I was quite surprised when the dating turned out to be about 8-lakh years old,” she said.

However, the dating of the tephra remains debatable to this day, with many in the geoarcheological community locking horns over which Toba eruption timeline it belongs to. Geologists and archaeologists from America, Germany, the UK, Canada, Australia and Taiwan have argued on the dating of the tephra, and study it closely to this day.

Protecting their geological heritage

Villagers at Bori Budruk continue undeterred in striving to protect their geological legacy. In 2018, fencing was done in a neighbouring village of Salwadi for about 700-metres to protect a part of the site. Apart from this, signboards were also erected, detailing the significance of the tephra. “We need funding desperately as all this money is mostly coming out of our own pockets,” Amol said.

Earlier, the tephra lined the Kukadi riverbanks across 12 villages, with Bori Budruk having the highest concentration. It is now coating some stretches of the bank and is patchy.

In his 60s, Ranjan Jadhav from Bori Budruk said they never thought the sandy substance they saw near the river would be so significant.

The Kukadi river flowing through Bori Budruk is used by the villagers for domestic purposes and agriculture. The community maintains a watch for pollution, sand mining and even visitors coming to the river bed. Photo credit: Manjula Nair

Reminiscing on the earlier days, he said, “People used to walk down to Bori Budruk from Narayangaon about 16-km away. There was no road, nor any vehicle. A handful had cycles. We would spot Mishra, but nobody gave her a second glance. At that time, we never really knew that it would be something so big.”

“It is 34 years since then and now ‘tephra’ is a word that’s part of our common tongue,” Jadhav said.

Sudha Vaddadi a geological consultant who was formerly associated with the Geological Survey of India, said the villagers are doing an exemplary job of conservation. In June 2019, when the villagers had convened a meeting with stakeholders for suggestions on conserving the site, Vaddadi was one of the experts who was called in, along with Rajguru and Mishra.

“They are doing commendable work trying to protect this heritage site, and transform it into an eco-tourism spot,” she said. “Unfortunately, in India, not much is done in terms of heritage conservation and protection. Most of these sites are dilapidated and their significance is undervalued. For the villagers to come together and do so much is very inspiring.”

Jadhav is now worried about the legacy of the tephra. “Here, the tephra is the stuff of local lore,” he said. “All the little children know about this. Our generation did not know, and we did not do much to protect it. The current generation is doing the best they can. Let us hope it will be enough.”

This article first appeared on Mongabay.