Hemp: The Secret Component in India's Stunning Ellora Caves

Occupying an imposing cliff, India's Ellora Caves were declared a World Heritage Site by UNESCO in 1983. The 34 buildings and spaces they house include Buddhist, Hindus and Jain temples, which existed simultaneously. As a result, they have been upheld as an example of the religious tolerance that existed in the country's ancient culture. 

Archaeologists and researchers had previously studied the reliefs and sculptures at Ellora from an artistic and anthropological perspective. However, a new, detailed analysis of the material with which the buildings were constructed revealed why they have been preserved intact for so long. And that secret is none other than hemp.

Two researchers found traces of the plant in the adobe mixture used to make bricks and ornaments at Ellora. On 10 March Rajdeo Singh, a chemist specialising in Archeology, and MM Sardesai, a botanist, released their results in the journal Current Science.

Although the hemp is present in low percentages, the researchers stated in an interview that hemp, even if constituting just 10 per cent of the mixture, if properly mixed with sand to make the adobe, could enable the buildings to remain standing for more than 1,500 years.

Hemp fibres appear to be of higher quality and to last longer than those of other plants also used for construction. In addition, the plant's abundant resin helps materials to adhere to each other. Hempcrete disperses heat, is fire-resistant, and provides great acoustic insulation, so it has not been ruled out that the monks who inhabited Ellora used it to create relaxing settings apt for meditation.

According to the researchers, the characteristics of this peculiar building material were well known by those who employed them in India. It helped to reduce pest problems, regulate the temperature of the caves, and prevent fires. The importance of the discovery stems from the fact that similar monuments of the same age, but with structures devoid of hemp, have begun to crumble, while Ellora still stands strong.