Moyar Gorge: Where the Continents Collided for a Billion Years

Joel Sherjin

A convergence point for Tectonics, Rocks, and Tigers in the Segur Plateau of Northern Nilgiris

The Moyar Gorge has always been a bit of an enigma, hidden from the public eye. This canyon is an indispensable part of history, geology, and folklore and is the best-kept secret of the Segur Plateau. Its mystery is partly geographical; it hides within three Tiger Reserves, making access almost impossible. Perhaps Moyar is best experienced as an idea, a wonder that captures imagination without being spoiled by too many footprints. It is a major geographical feature: a 20 km long and 250 meters deep fracture on the landscape.

After many years of casually ignoring the horizon, I still remember my first conscious encounter with the gorge, about sixteen years ago, along the winding and steep Kalhatty Ghat road, where the horizon opens between the long protruding finger-like ridges of the North Nilgiris mountains. Spread out in front of me were the vast landscapes of Segur and the tiger reserves of Mudumalai, Bandipur, and Sathyamangalam. This is an endless pale green and brown carpet, with undulating scrub jungle that is home to a vast array of fascinating wildlife, including tigers, elephants, and many rare mammals including hyenas. Cutting right through it, sharp and unavoidable, was a massive scar on the land: the Moyar Gorge. It stretched across the valley like someone had slashed open the earth with a giant’s knife. For a moment, it reminded me of the canyons of Colorado, and I realized then how badly I had underestimated the size of the gorge. Since then, after living a stone’s throw away in the Segur Plateau, I’ve had chances to see Moyar from different angles and hear countless stories about its rocks, its wildlife, and its mysteries. My interest in the origin of the universe and continental tectonics was only further fuelled when Pranay Lal opened his book Indica with the geologic significance and majestic half-page picture of the Moyar Gorge. Further readings on tectonic plate movements by some of the doyens like Dr. T.R.K. Chetty and Gunnell have always mentioned the Moyar Gorge and the Moyar shear zone at the centre of the continental assemblage activities.

View from the Kalhatty Ghats on the Northern slopes of Nilgiris

The Origin of the Gorge

The Moyar Gorge is one of the deepest gorges in South India, 260 meters of a near-vertical drop, running about 20 kilometers long. The Moyar River runs through it from west to east, heading to the Bhavani Sagar Dam, tumbling in mighty waterfalls along the way. Over millions of years, rainwater rushing down the northern, rain-shadowed slopes of the Nilgiris has patiently chiseled the rocks deep, exposing their hidden layers.

The origin of Moyar Gorge is more complex than the elephant corridor and other regulations that govern the surrounding areas. To understand the origins, you must think in terms of billions of years. The rocks in Moyar date back 2.6–3.0 billion years, almost as old as the Earth itself (the Big Bang was 4.5 billion years ago). Moyar sits on the Moyar Shear Zone (MSZ), a weak seam in Earth’s crust that has been active and reactivated for over 2 billion years by tectonic movements and volcanic activities. It separates two very different geological provinces:

Bird's-eye view of the Moyar Gorge with the northern slopes of Nilgiris visible to the left.

• To the north lies the Dharwar Craton, which comprises ancient granite and greenstone rocks that are tough and resistant. This is part of Bandipur Tiger Reserve to the western end of the gorge and the Talamalai plateau in Sathyamangalam along the majority of the gorge’s length. These are tough rocks and explain why they are higher and have eroded less over time.

• To the south lies the Southern Granulite Terrain (SGT): rocks that were cooked deep in the Earth under high heat and pressure, turning into granulites. Nilgiris has abundant tough, erosion-resistant charnockites, but the Segur is dominated by much younger amphibolite-gneiss formations and granitic gneisses along with pyroxene granulites. These rocks have been highly active and gone through many metamorphosis phases. The result is weak and erosion-prone rocks that have let the Moyar River dig deep and form the gorge. Also, this has left the soil in the Segur Plateau acidic, resulting in a unique dry scrub vegetation in the landscape.

Charnockite Rock

By ANBARASU THIRAVIYAM - Own work, CC BY-SA 4.0, Wikimedia

Gneiss Rock

By Ravi Mundkur. Wikimedia

The Moyar River, as all rivers do, found this weak zone in the suture zone of Dharwar and Southern Granulite Terrain and exploited it by eroding it over and over. These are two different land masses that collided and moved against and along each other and evolved with volcanic and molten movements independently, just as water and oil boiling in a jar behave distinctly and yet share a defined boundary. Over time, the river gnawed much deeper into the seam until the gorge we see today emerged. The bottom of the gorge still holds the tough and older greenstone belt, which has resisted further erosion, setting the depth at today’s ~260 meters.

Google Earth View of the Gorge with rivers from Nilgiris, the Southern side of the gorge draining into Moyar while eroding the rocks. The Northern side is relatively firm as visible in the image

The Gondwana Remnants

To really place Moyar in a tectonic evolutionary timeline context, you have to zoom out to a time when the first continental crust formed, 2.5 billion years ago, comprising greenstone belts that solidified underneath. The Dharwar Craton, which makes up most of the Indian Peninsula, also formed around the same time. This event was followed by many continental movements, collisions, and volcanic activities, where most of the mineral compositions of rocks kept changing. Most of the old rocks here persisted until the supercontinent Gondwana was formed, a relatively stabilizing event compared to the earlier 4 billion years of tumultuous past.

Now, say 500 million years ago, the world as we know it was a single mass of continent Gondwana, where India was welded to Madagascar, Australia, Antarctica, and Africa. Moyar’s rock layers were formed then, in millions of years of ancient volcanic eruptions and continental collisions.

When Gondwana began breaking apart, Madagascar was one of the last to drift away from India, leaving Moyar’s scar, a weak suture point, as a reminder. Even today, odd species like the purple frog, a living fossil that emerges only during the monsoon, testify to that shared past as they are seen only in the Western Ghats and the continuity of it as seen in Madagascar, just like a separated-out puzzle block. Even the Palghat Gap, south of Nilgiris, has an aligning piece in Madagascar, the Ranotsara Gap.

Later, when India raced north and smashed into Asia (just 50 million years ago, which is quite recent by geological standards), the Himalayas rose, monsoons were born, and the stage was set for the forests, grasslands, and elephants that now roam around the Moyar landscape. The climatic conditions made Nilgiris a high precipitation zone, which continuously drained waters along the Segur Plateau down to the Moyar Shear Zone, which had weaker rocks and kept eroding it to this day, forming the deep gorge. The stronger Dharwar Craton with greenstones on the other side, established itself as a frontier wall, resisting erosion.

If Moyar seems otherworldly, it’s because it carries the memory of a time when continents were shuffling like puzzle pieces and oceans were being born and erased. The gorge is a key bookmark in Earth’s story, a place where the present-day forest sits atop few billion of years of tectonic drama.

Moyar is not Just about Stones

Moyar is more than rocks. It is alive and kicking and is the centre of several socio-political and natural history dramas. The gorge and the Segur Plateau are part of the Nilgiri Biosphere Reserve (UNESCO), one of the richest biodiversity hotspots in India. The gorge is a critical elephant and tiger corridor, connecting the Western Ghats with the Eastern Ghats. Elephants migrate here seasonally, tigers patrol its edges, and rare mammals like hyenas, blackbucks, and even possibly the four-horned antelope graze the vast plateau of Sigur.

The River Moyar, a perennial one, is the last remaining large water source in harsh summers for the vast animal life in the area, making it a green winding line of oasis in the brown dry landscape. Elephants and other animals make arduous treks down this steep gorge where there is access paths to enjoy the green grass and water and make it back for their continued journey through the vast Segur Plateau. The Moyar river itself is home to the majestic humpback masheer and shares some endemic loaches with the nearby Cauvery tributaries.

In the last 100 years, the gorge was extensively used by the British as hunting grounds in the early 1900s with gunshots echoing the walls of the gorge, and later, bandits like Veerappan used the gorge largely as a hideout passage and also a poaching ground. Dam projects in the mid-1900s also brought a lot of anthropogenic influence to the place, along with the growth of fishing in the gorge, especially around areas like Bellimeenkadavu. The declaration of Mudumalai Buffer Zone around 2010 tightened access to the gorge for the public.

Today, though, Moyar is harder than ever to visit. The last access to the public ended in 2021, when Masinagudi’s eco-safaris were shut “temporarily” for COVID. They never reopened. Overnight, seventy-odd jeeps went idle, and families who had survived on ecotourism were left stranded. The gorge, meanwhile, slipped back into secrecy.

Yet, if you know where to look, Moyar still reveals itself. From the Mudumalai Tiger Reserve safari, you can ask your jeep driver to make a detour to the waterfalls viewpoint. There, the Moyar River drops almost 200 meters straight into the gorge — the same river you may have quietly crossed beside the Mudumalai elephant camp just minutes before. The sight is staggering: water vanishing into a green abyss.

And if you prefer the long view, some of the best panoramas of Moyar are from the Nilgiri hilltops at Kodanad, Ebbanad, or Sholur, where the gorge cuts the horizon like a scar on the landscape. Access is also possible through Siriyur village or more directly via Moyar village, a short drive that brings you to the edge of one of India’s greatest geological wonders, a view restricted to the forest department and their lucky guests, and an odd researcher or a faunal survey volunteer.

Why Moyar Matters

• It’s ancient: Its rocks are 2.6–3.0 billion years old.

• It’s a tectonic boundary: A scar where two continents stitched together.

• It’s a natural lab: Recording ultra-high temperature metamorphism.

• It’s an ecological corridor: Linking tigers and elephants across Western and Eastern Ghats.

• It’s a wonder: A canyon with cliffs, waterfalls, and wildlife.

The Segur plateau and the Gorge at the far end as shown in an Anglo-Indian movie, Harry Black and the Tiger, in the year 1958.

The Moyar Gorge is more than a pretty view. For me, Moyar will always be tied to the vast horizon, the gorge stretching like a scar across it, proclaiming the continental shifts and endless time the landscape has been a witness to. Years later, after living close by and hearing countless stories, I realize Moyar is not something you simply “see.” It’s something you imagine through the insights on the formation of these landscapes by the likes of Dr. T.R.K. Chetty or the writings and speeches of Pranay Lal. And maybe that’s Moyar’s greatest gift: in a world where everything is overexposed, Moyar remains mysterious, untamed, and does not explain itself easily in 140 characters or an instagram carousel.

If you’ve made it this far, thank you for sticking with a long-form piece. If you have a moment, please scroll to the bottom of this page and share your thoughts. I’d be deeply grateful. 

References

• Gunnell, Y., & Harbor, D. (2008). Structural underprint and tectonic overprint in the Angavo (Madagascar) and Western Ghats (India): Implications for scarp evolution at passive margins. Journal of the Geological Society of India, 71, 763–779.

• Ramakrishnan, M., & Vaidyanadhan, R. (2010). Geology of India, Vol. 2. Geological Society of India.

• Sharma, R. (2009). Cratons and Fold Belts of India. Springer.

• Indica, Pranay Lal, and his many talks I have attended or watched on YouTube.

• Proterozoic Orogens of India, Dr. T.R.K. Chetty and his many lectures.