Science

New geometrical lines discovered in Thar Desert

The first author of the paper, Carlo Oetheimer, explains: “The Boha geoglyphs are clearly manmade as the main unit is a giant spiral, but they have been eroded due to the cars running over the lines lately.”   | Photo Credit: Yohann Oetheimer

Using Google Earth images, drone observations and field visits, two independent researchers from France have identified eight sites around Jaisalmer in the Thar Desert, that show linear features resembling geoglyphs. Geoglyphs are large, un-explained geometrical patterns on land usually proposed to be man-made features.

The largest concentration of geoglyphs is reported from southern Peru, covering an area of about 1,000 square km. The new paper published in Archaeological Research in Asia notes that the identified geoglyphs in the Thar Desert cover an area of about 6 square km.

The authors’ main area of interest was Boha, a small village 40 km to the north of Jaisalmer where they noticed a series of concentric and linear features. They named these features Boha geoglyphs and suggested that the features could be at least 150 years old. “It is however conceivable that they were built at the beginning of the British colonial period, in the middle of the 19th century,” adds the paper.

 

The first author of the paper, Carlo Oetheimer, explains in an email to The Hindu: “The Boha geoglyphs are clearly manmade as the main unit is a giant spiral, but they have been eroded due to the cars running over the lines lately. So, they are clearly not formed by weathering or another natural phenomenon.”

Dr. Amal Kar, formerly with the Central Arid Zone Research Institute, Jodhpur, who has been studying the Thar Desert for nearly five decades, disagrees with the above conclusion. He suggests that the observed features might have been formed naturally, but degraded over time due to both natural and human-related causes. “The rocky terrain between Jaisalmer and Ramgarh in the north is home to a typical weathering feature, especially over the iron-rich sandstone and shale beds. Here, extreme aridity and high temperature lead to slow geochemical translocation of minerals for centuries, such that the heavier minerals like iron and manganese move away from the lighter minerals, which lead to the gradual formation of alternate bands of harder and softer mineral concentrations. With time the areas with softer materials get slowly eroded, while the harder ones stand out, producing the typical concentric or box-like geometric features,” he explains.

 

He adds that such features, both small and large, can be found in the similarly disposed rocky terrain of all the global deserts, but hardly in the semi-arid areas due to higher rainfall.

Considering the uniqueness of such micro-geomorphic features in our country, he pleads for appropriate conservation measures, especially from wanton construction activities and uncontrolled tourism. “Attributing such features to humans should be considered with caution and only when natural explanations fail absolutely,” he adds.

Memorial Stones

The French authors also suggest that the lines could be contemporary with the neighbouring memorial stones. During the fieldwork in 2016, the team located a total of nine monoliths with the most imposing one being a truncated conical pillar measuring about 1.60 metres. They also located four memorial stones with sculptures of Hindu deities (Krishna and Ganesha).

“We still need to complete our study, going back to India, making an anthropological survey with the help of local researchers, and bringing all the equipment in order to date the geoglyphs. We would like to date the glyphs with the thermoluminescence method,” adds Carlo Oetheimer.


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Printable version | Jul 30, 2021 11:50:15 PM | https://www.thehindu.com/sci-tech/science/new-geometrical-lines-discovered-in-thar-desert/article34716927.ece

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