Caves are depictions of ancient Indian culture and natural history that exhibit either explicit carvings or plain natural features. Caving itself has become a much sought out activity that offers experiences of a rendezvous with history and natural beauty. The Central Indian region abounds in majestic caves – marvels of ancient Indian architecture. The famous Elephanta caves near Mumbai are located on an island hill – a world heritage site belonging to the 6-7th centuries AD with sculpted statues of Hindu gods and goddesses cut out of sheer rock facies. The Kanhari Caves, situated amidst the lush green forest of Borivali National Park in the heart of Mumbai is a rock cut cave built in the 2nd to 9th century AD and adorns a huge statue of Lord Buddha. Another example of wonderful architecture, sculpture and paintings is the Ajanta caves in the Sahyadri hills, constructed out of the volcanic lava and the Ellora Caves built during the 5th and 11th century AD. The amazing Bhimbetka caves in Bhopal are a repository of largest pre-historic culture in the country. Other important caves in this region are the Bhartrihari on the banks of River Shipra and Pandav caves located at Pachmarhi. The Udaigiri caves in Sanchi are reflections of legendary rule of the Gupta dynasty, and the Bagh caves in Dhar district of Madhya Pradesh with its painting and sculptures depict the Buddhist influence in India.
The State of Chhattisgarh, as is true for large portions of Central India, also abounds in caves predominantly excavated by drip water on limestone deposits resulting in mystifying shapes of stalactites and stalagmites and limestone pillars. The Kailash Gufa which lies near the Tirathgarh waterfalls located in Kanger Valley National Park in Chhattisgarh holds fascinating formations of limestone pillars. Nearly 200 metres long and 55 metres deep, the features of the underground caves are also worshiped as depictions of Lord Shiva. The Dandak Caves, which are larger, lie below a hillock and is replete with calcium carbonate formations. The entrance to the cave is however unique with an intricately carved rock façade. Mandip Khol and Singhanpur are other caves in the State that has a rich biodiversity and geomorphic value, the latter being still largely unexplored.
Caves and Climate change
As karst topography is a direct outcome of water dynamics, stalagmites and stalactites maintain records of past dry and wet seasons and thus climate change. These are, in essence, tropical ice cores forming over thousands of years. Each layer of the rock contains important chemical traces that help determine what was going on in the climate thousands of years ago, much like the ice cores drilled from Greenland or Antarctic. Stalactites and stalagmites in fact maintain a near-continuous record of the climate from 25,000 years ago to the present. Stalagmites are formed as rain water, mixed with calcium carbonate and other elements, makes its way through the ground and onto the cave floor. As this solution drips over time, it hardens in layers with light and dark laminations, creating a column of rock. By cutting open each stalagmite and taking measurements of their chemical contents relative moisture during various periods in history starting from the oldest layers at the bottom to the present at the top can be determined.
The caves of Chhattisgarh have been studied extensively by researchers to determine monsoon variability and tropical climates of the past. In a recent study by A Sinha, et. al. 2011, titled The leading mode of Indian Summer Monsoon precipitation variability during the last millennium; Geophysical Research Letters, stalagmites from a cave named Jhumar, located near Jagdalpur have been accessed. The actively growing stalagmites were selected from poorly ventilated chambers, located at a considerable distance from the cave entrance, ensuring that there was a near constant and environmental stability in terms of temperature and humidity. A reconstruction of monsoon precipitation variations created a 1400 year record, which captures the major short term droughts of the 20th century and also suggests a shift towards enhanced monsoon precipitation from the later half of the 17th century. The results are corroborative of the various findings of stalagmite study world over.
Cavernicoles of the Kotumsar
The subterranean Kotumsar caves, the most biologically studied cave in India, were discovered in 1958 by Prof. Shankar Prasad Tiwari, a pioneer in rock art research, cultural geography, archaeology and natural history of the Dandakaranya region. The folklores however, say that the caves were discovered way earlier by local hunters – chasing a porcupine that led them to the caves. The caves, located in the jungle clad Kanger Valley National Park in Bastar, is a marvel of nature. Kotumsar lies near the white cascades of the Tirathgarh waterfalls some 38 km from Jagdalpur district. The limestone caves have several chambers and hold the record of being the second longest natural cave systems in the world. The entrance to the caves is a vertical narrow and twisted fissure in the wall of a hill, about 15 metre in length and the deepest portions of the caves remain in complete darkness at all times. Visitors are prohibited within these precincts. The cave is honeycombed in its structure, consisting of several irregular chambers. The main tunnel of the cave is nearly 500 metre long and has several lateral and downward passages. The roofs and walls of the different chambers are lined with colourful dripstone formations resulting from the precipitation of calcite-dissolved carbonate lime. The chambers of the cave are floored with either rocks or pebbles of various dimensions or by surface-derived soil/clay deposits. Amidst the darkness unusual formations evoke imaginations that make it an experience of a lifetime. Torches and solar lamps light up the damp walls and a careful round of the echoing chambers reveal tortuous rivulets and puddles – making it an apt background for a chilling adventure. The cave is subject to frequent flooding during the monsoon which generally begins in the middle of June and continues until mid October.
Cave environments have long been known to host ecosystems that are amongst the most fragile and unusual. Perpetual darkness, almost constant geophysical factors, high humidity and low energy input are general characteristics distinguishing the cave environment. The organisms of such ecosystems often show a high degree of specialised physiological adaptations, behavioural adjustments and morphological alterations. Species might colonise cave environments either to seek temporary shelter or in order to escape from persistent adverse environmental conditions on the surface. Each cavernicole species occupies a particular ecological niche in the cave which is related to their degree of evolutionary adaptation to the subterranean environment. The subterranean environment can be divided into three different zones depending upon the characteristics of constancy of their immediate geophysical parameters
The twilight zone: Immediately near the entrance where light intensity, humidity and temperature vary with the external environmental conditions. The Kotumsar twilight zone is very short, just about 2 metre and as such the flora and fauna found in these regions are excluded from taxonomical studies.
The transition zone: It runs till the point where air-current, humidity and temperature becomes constant. It is an area of almost complete darkness. Species found here generally can also survive in the external world.
The deep zone: Subject to complete darkness this zone is occupied by specialised cave-adapted species which are generally unable to survive in the external environment. The life forms here have either lost their vision completely or have very regressed vision with highly developed extra-ocular sensitive organs and no body colourisation/albinic. The organisms have the ability to withstand prolonged starvation and to tolerate prolonged hypoxic conditions.
Species that have been broadly identified inhabiting the deep zone of the caves are Rufous Horseshoe bat, Ashy Leaf-nosed bat, Fungoid frog, Hill stream loach, Giant crab spider or the banana spider, Cave centipede, millipedes, Cave cricket, Guano moth, copepoda, pillbugs and snails. It is interesting to note that the entire ecosystem of the caves is dependent on the guano deposits of the bats that inhabit the precincts. Three species that warrant special mention are the hill stream loach, Nemacheilus evezardi, that exhibit physiological and behavioural functions that are unique with albinic or depigmented form with highly regressed eyes; the cave cricket, Kampiola shankari (name coined to honour Prof. Shankar Tiwari), with relatively small eyes, invisible ocelli, sensitive sensillae, faint body colourisation, very long antennae and the presence of very rigid sound producing organ which appears during imaginal moult process of development; and, a new species of Syncarida, Chilibathynella kotumsarensis, recorded from the Kotumsar Cave – the only fourth known member of the family Parabathynellidae and the sole representative not only within Asia but in the entire global tropical zone.
However, sections of the caves also serve as worshiping place for locals and a specifically identified stalagmite is considered the mark of Lord Shiva. Increasing number of worshippers deposit foodstuff and burn incense leading to progressive pollution of the inner precincts. Observations suggest that the Kotumsar Cave hosts a rich biological community. Robust conservation measures should be employed to ensure this fascinating environment and the resident cavernicoles are preserved for future generations.