Weathered by nature

Sometimes, when the conditions are just right, weathering processes give birth to beautiful arches that allure both tourists and geologists. So, come explore one such creation in Malavalli, says S S Chandrashekarmath

Halaguru in Malavalli taluk, Mandya, is like a hub of tourism surrounded by some very popular tourist spots, like Shivanasamudra Falls, Shimsha Falls, Muthathi, Bheemeswari and Basavana Betta. These places are a favourite with trekkers also.

Pretty soon, Malavalli will have another feather in its cap with the completion of the Martyrs Memorial Park, a tribute to the brave soldiers who laid down their lives during the during the fourth Mysore-Anglo War. The British forces were led by Colonel Arthur Wellesley in this war. 

The highlight of this region, however, happens to Bheemana Kindi Betta, a natural rock arch formation of a unique kind.

Bheemana Kindi is located nine km from Halaguru, in a dense forest area of the Kabbal State Forest. The top of the hill has a rock arch, which is an intricate gift of nature. This iconic feature possesses a certain understated allure. It takes about two hours of trekking to see the Bheemana Kindi Rock Arch. 

The Rock Arch is visible only when we reach the topmost point of the hillock. It is located 3,500 feet above the sea level and about 1,500 feet in height from ground level. 

The Rock Arch is about 100 ft in height, with a length of about 100 ft and width of 50 ft. The Bheemeshwara Temple is located within the arch. Mondays and Fridays are the only days of worship. Hence, on these days, footfalls of devotees who throng to seek blessings from the deity are the highest.

Much of the origin of the arch is related to the Mahabharata (during agnathavasa). There are many stories surrounding the formation of the cave. Some believe that while Kunti was bringing food to Bheema, she lost her way in the forest. To rescue her, Bheema hit the topmost cliff with his mace and paved an entry through the arch for his mother. 

Formation of rock arches

Natural rock arches are geological formations, where they are formed by the natural selective removal of rock, mainly by the process of erosion, when certain processes dissolve the crystalline cement, thereby destroying the rock matrix. The erosion may be because of sea, river or  wind. 

Rock arches are formed depending upon the geological features of the hill. There are wind created arches, coastline arches, water eroded arches, cave eroded arches, glacier arches and much more.

In some places in the world, natural rock arches are truly natural bridges because there are roads or rail roads running across them. Carter Caves State Park and Natural Bridge State Resort in Kentucky are few examples.

Some of the largest natural rock arches are the Fairy Bridge or Xianren Bridge, Jiangzhou Immortal Bridge and Gaotun Natural Bridge in China; Landscape Arch, Kolob Arch, Rainbow Bridge, Sipapu Natural Bridge, Stevens Arch and Morning Glory Natural Bridge in the USA and the Aloba Arch in Chad.

Natural Rock Arch in Tirumalabetta, Tirupathi, Rock Arch Bridge of Gulachawadi in Maharashtra, Sidlaphade near Badami and Yana in Sahyadri mountain range in the Western Ghats in Karnataka, are some of the most famous rock arches in India.

Unique creation

The formation of the Bheemana Kindi Arch is related to plate tectonics (tectonic geomorphology) and more particularly orogenic processes of mountain building activity rather than erosion. 

Metamorphism is a step involved in this process. Surprisingly, it is linked to lichen activity, which is a microbiological weathering process. The lichens are neither animals nor plants and belong to a different kingdom. They are composite organisms consisting of symbiotic pairing between an alga (phycobiont) and fungus (mycobiont).

The hilltop is colonised by the growth of millions of fructose (crusty) and foliose (leafy) and variety of lichens which produce numerous lichen acids and act as bio-weathering agents and disintegrate the rock matrix. It is probable that during the orogenic process, large joints and fractures might have been developed. 

These lichens may have colonised and disintegrated this portion, detaching it from the hill, giving rise to the arch structure. The geomorphology with an almost vertical steep slope has also contributed to the arch formation.

Rock arches are common in limestone, sandstone and shale rocks because they are susceptible to weathering. But, the multi-coloured metamorphosed gneissic-granite rock in Bheemana Kindi is very hard, less prone to weathering agents and can withstand erosion from natural elements, but not from lichens.

There are over 1,500 varieties of lichens. There are nearly 700 different compounds of lichen acid. Lichens colonise in a green and clean environment. Such features are rather rare in rock arches, making Bheemana Kindi a unique and exclusive creation. 

Not only is Bheemana Kandi Hill a famous tourist and trekking spot, it is also of great academic interest to microbiologists, structural geologists and geochemists.