The lush monsoon-watered landscape of Malwa unfolded before us as we traveled from Dhar to Mandu. This road was familiar to us from eight years ago. We came to a halt near a park-full of fibreglass dinosaurs. The area around the museum of fossils had been converted to a children’s park. There was a wall around it, and several food stalls. Quite a change from the emptiness I’d remembered. As I approached a turnstile, a young man appeared and said “Five rupees for entry and another twenty five for the camera.” The museum was locked, but a lot of people were taking selfies against the dramatic background.
The Malwa landscape is mostly flat, as you can see in the photo below. This is one place on the Malwa plateau where the landscape indulges in a bit of drama. A little stream has cut a deep gorge into the plateau, showing that this is part of the Deccan traps. You can see the characteristic layer-cake appearance of the gorge, created by a few lakh years of volcanism (that’s a few hundred thousand years) which killed off the dinosaurs and created some of the fossils which you can see in the museum. The layers are formed by clay trapped between successive flows of lava. Above the basalt you can see the last 65 million years of strata.
If the land is old, human civilization here is also old, as humans go. Archaeology has yielded up Paleolithic hand axes, Microlithic arrowheads, and Chalcolithic tools, leading up to the recorded history of the immediately pre-Buddhist era. The earliest records talk of large cities and vast trading networks which connected the known world, bringing Central Asian and Greek pilgrims to this region of the world, and surely sending some questing abroad. It is easy to forget the depth of this history when you talk to the locals who cater to tourists. The farmers who till this monsoon-lush, but otherwise dry, landscape will hardly believe that slightly deeper tools could turn up the remnants of soil laid down in the time of Vikramaditya. Increase the length of the tool a little more, and you could be exposing the soil that Buddha’s contemporaries walked on. But that you would have to dig twenty feet to get to Paleolithic remains. Deep history is so deep.
The region of the Western ghats around Satara and Pune are full of large plateaus and oddly shaped peaks. When you travel through them, the first impression you have of the mountains is that they look like a layered cake. I stood at the Thosegarh waterfall (featured photo) and found that even the monsoon-fed vegetation could not hide this appearance. The layers are a succession of lava flows, laid down in a massive burst of volcanism 60 to 100 million years ago. These successive layers of lava are called the Deccan traps. I found it hard to estimate the thickness of the layers by eye, but going by the heights of trees, perhaps they are between 50 and 100 feet thick. Since each layer of lava covers a considerable area, this means that each burst of volcanism would have lasted long and spewed out immense amounts of rock and ash. Not only would this have killed all life where it flowed, it would have dimmed the sunlight reaching the earth, and contributed to a mass dying of vegetation around the world.
In the 60 million years since it contributed to killing off dinosaurs, the traps have weathered. Today we see them as flat topped hills, cut through by deeply eroded valleys. Some of the waterfalls lead down to rapids extremely suitable for white water rafting. In other places there are very wide valleys. The town of Satara, which you see in the photo above, lies in the extreme western end of the rain-shadowed region of the Deccan. As a result it gets sporadic monsoon rains, enough to keep it green. The urban sprawl gets its drinking water from the river Umboli, which arises in the Kaas plateau, about 25 kilometers away. Traveling in this area, I saw many high plateaus. At one point each of them must have been home to the variety of flowering herbs and bushes whose diversity is now mainly visible in Kaas.
When you reach the top of one of these plateaus you see exposed rock everywhere. This is the volcanic rock called laterite, formed by weathering of the traps. You can see the dark porous rock peeping out from the low cover in the photo of the Kaas plateau above. There is hardly any soil. What little there is forms in little depressions in the rock. This area is covered by tiny herbs: mainly the carnivorous bladderwort (Utricularia) and sundew (Drosera) species, and tiny coexisting herbs. Between such rocky outcrops, there are deeper fissures where a little more soil can collect. There are higher bushes such as the Topli Karvi and arrowroot. There are very few trees on the plateau. What little soil forms is constantly removed by rain and wind. It is a marginal environment where extremely specialized plants grow. Twenty meters below the top, soil can accumulate, and the vegetation changes quite dramatically. It becomes characteristic of the rest of the Sahyadris. As a result, these high plateaus are like islands: the flora of each plateau is isolated from those of its neighbours.
When you walk through the Kaas plateau your eyes take in the evidence that geology determines ecology, that life is shaped by the land.
We drove to Pune in the weekend, over a road blasted through the heart of the geological bomb which killed off the dinosaurs. The Mumbai-Pune expressway is probably the busiest road in India. Still, there are times when you can take your eyes off the road to stare at the incredible mountains around you.
During the monsoon the mountains are covered in a carpet of electric green. Yes, there is such a colour; you have to travel here to find out what it is. In this season, with the brief winter on its way out, the grasses have dried out, turning into layers of gold against the red rock of the Deccan traps. These mountains are the Sahyadris, and the red rock is the dinosaur killer.
Go off the road. Stop when you can. Look again at the mountains. The most noticeable feature of the Sahyadris are the horizontal layers in the rock. Many years ago, sitting at a roadside dhaba, I asked a geologist friend about this. Between sips of tea he mentioned the phrase Deccan traps. These are successive waves of lava which flowed out of our planet’s largest volcanic event and killed off the dinosaurs.
A shiver goes through my spine even today when I sit and look at these six and a half crore (65 million) years old rocks. The continuous volcanism lasted for a few lakhs (hundreds of thousands) of years. The lava covered an area larger than that of Maharashtra and Madhya Pradesh put together. Ash, carbon dioxide and sulphur dioxide pumped out by the volcanos changed the climate, making it first cooler, then hotter, and turning the rain acid. The dinosaurs died out, along with most of the life on earth. The earth was barren for about half a million (5 lakhs) years.
When the volcanism ended and the skies began to clear, the mammalian takeover of the earth could begin. The next time you drive between Mumbai and Pune, look at the layer cake mountains around you: they are the reason you are here.
(Featured photo by S. R. Kiran, Mahabaleshwar ghats photo by Mark Richards, map from Princeton univ)
Head out of Mumbai, pass the Expressway and its food courts, and you soon come into impressive weathered hills. Strange shapes rise out of the land. Pass Pune, and head South, and you begin to see ranges of hills with a very characteristic feature: they seem to form gigantic layers or steps. If you look carefully at the far, mist covered, hills in the photo alongside you see these characteristic layers. They are volcanic features called “trappen” in Swedish, meaning steps. Successive volcanic eruptions created these layers.
A closer and clearer view of the steps is in this photo taken at the Thosegarh waterfalls south of the town of Satara. These layers are called the Deccan traps. It is thought that thirty thousand years of continuous volcanic eruptions laid down these layers of basalt over a huge part of the Indian plate. This happened while dinosaurs still roamed the earth. Since then the volcanic rock has worn down to a half million square kilometres area in the Deccan plateau.
This is the geology within which the Kaas and neighbouring kilometer-high plateaus stand. Over millennia, the basalt was weathered down by successive dry and wet seasons until it is a porous rock. You can see the weathered rock, called laterite, in the featured photo. Over this laterite is a thin layer of red iron-rich soil called lateritic soil. You can see in the photo alongside how poor the soil is. The grasses and the low herbs of these plateaus, including Kaas, barely manage to hold the soil together. Of all the things that damage this fragile ecosystem, tourists are the worst, although the construction of windmill farms and extraction of bauxite also harmful. Reading about this area, I discovered the word "inselberg", meaning island mountain. It is a very apt description of these plateaus: each stands isolated from others. The flora of each of these inselbergs is different from that in the surrounding lowlands. Environmental degradation of a plateau is like killing off the ecology of an island. It seems that of the 850 odd species of herbs identified here (including genera found only here), more than 600 are on the IUCN red list of threatened species.
The ministry of the environment lists many benefits that these ecosystems provide, including medicinal plants. Another ecosystem service provided by this fragile system is the recharging of the surrounding water table. As you can see in the photo here, the grasses and herbs trap water into little monsoon pools. This water is then absorbed by the spongy laterite rocks. In the absence of the flora, the water would run off too fast to be soaked up. The average annual rainfall here is between 2 and 2.5 meters, so this is quite a service!