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Most of India's geography has been shaped by rivers or rainwater, with some wind-sculpted formations. Ladakh offers picture-perfect, textbook-worthy examples of how glaciers have shaped landscapes. Here are some of the features you can find:
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Arête: the jagged ridge that forms the glacier slopes.
Horn: where two or more arêtes meet, or the peak of a glacier.
U-shaped valley: unlike the V-shaped valleys formed by rivers, glaciers move slowly and carve out deep U-shaped troughs - the most distinct glacial formation.
Moraine: when a glacier is moving through a valley, much like a river, it carries along coarse debris of pebbles, which is deposits along its path - this is known as moraine. Imagine drawing a line in wet sand, as you might have done at the beach. The sandy ridge that forms along the edge of your line, can be likened to lateral moraine. The sand that marks where your line ends, is like the terminal moraine. The debris deposited by a glacier along its channel is the medial moraine.
Tarn/glacial lake: high along the ridges of a glacier, meltwater collects in depressions and are dammed by debris/moraine. These are glacial lakes or tarns. Sometimes, the moraine that dams such lakes is disturbed or dislodged due to earth-moving activities, earthquake tremors, a buildup of meltwater pressure, avalanches, among other reasons. This causes the entire lake to gush downslope, in what is known as a glacial lake outburst flood (GLOF). GLOFs are among the most dangerous glacial features and have become more prevalent due to climate change (increasing glacial melts).
Braided river: when water flows along the slopes of a melted glacier, where a lot of debris has been deposited, it forms a river with multiple, plait-like channels (as the water has to navigate past all the deposits). The sandbars or islands formed within braiding rivers are temporary and ever-shifting, and the river channels too.
Drumlins and erratic boulders: long, tear-drop shaped hills of rock, sand, gravel (drumlins) or large boulders erratically abandoned over a landscape, are remnants of glaciers.
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Ladakh falls in the trans-Himalayan zone - one of the world's most remote and inaccessible regions, defined by the Himalayas to the south, and the Tibetan Plateau to the northeast. Located to the leeward side of the Himalayas, the trans-Himalayan zone experiences lesser precipitation which defines Ladakh's short agriculturally-productive season. This seasonal productivity also affects the flora and fauna, which is adapted to extreme conditions, and most species occur in sparse populations.
*Recently, there has been some controversy about the term 'trans-Himalayan', and there may be tectonic shifts in nomenclature soon!
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For the geo-enthusiasts, driving through Ladakh is an enriching experience. While most places are promoted for their aesthetic or cultural value, here are some geographical notes on destinations and what they have to offer:
The Ladakh Rocks & Minerals Preservation Study & Museum, Leh (located near Shanti stupa) is a small one-room, passion-driven collection of minerals, fossils, precious and semi-precious stones - well-worth a visit to understand the geological wealth of the region.
Petroglyphs along the Indus: the Upper and Lower Indus stretches have numerous petroglyph sites - inscribed rock art depicting scenes from past civilizations. Interestingly, studies of petroglyphs in Ladakh draw parallels to those in Central India and Tibet, and some date back to the Neolithic (~7,000 - 1,000 BCE) or Early History, while most can be dated to the Bronze or Iron Age (~1,500 - 600 BCE) in India.
*Psst, missed the Geosophy edition on Goa's petroglyphs? Access it here!
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Lato village: a two hour journey south-west from the town of Leh, in the trans-Himalayan kingdom of Ladakh in India, takes you past Buddhist monasteries, territories of medieval chieftains, and pasturelands. If you follow the Indus River, past scree slopes where blue sheep graze and golden eagles hunt, you'll find yourself in a little village called Lato. Most everyone will remark on the stark landscape of sheer crags, but for a geologist - this landscape tells a more fascinating story.
Lato's settlement and its electric lines are dwarfed by a staggering ridge of serpentine, a group of blue-green minerals that mark where the continental plates of India and Eurasia collided. As the cataclysmic event unfolded, the Indian plate slipped little by little under the Eurasian plate, the pressure and temperatures compressed the rocks into the telltale serpentine. As the Indian plate crumbled slowly over years, mountains arose at the edge of two former coastlines - pushing marine fossils, and corals, ever higher to summits that defied any other on Earth. These crags form what is known as the Indus Suture zone where two continents are being stitched together.
What's most incredible is the Indus river that flowed before the plates collided, and continued to carve its way as the rocks crumpled into mountains, and the mountains into ridges. Is it any wonder then that Indians consider rivers like the Indus sacred - they have after all, seen the birth of the Himalayas!
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Fossils in Hemis, Kargil and the Indus-Suture zone: exciting as it is to find fossils of ancient marine creatures, ammonites, trilobites, some plant leaves, in Ladakh, the geography behind them is just as fascinating. Ladakh emerged from a once-submarine/underwater landscape under the Tethys Sea, and the fossils are testimony to its watery past, and the rising of the Himalayas.
Hotsprings in Nubra and Puga Valley: when magma bubbles close to the surface of the earth, it causes the water to spurt up in geothermal geysers or springs. Ladakh's volatile past, and its tectonically unstable present is writ large in its geothermal springs - one of the contenders for renewable, natural energy in the area. As with hotsprings elsewhere, these also have some mythical, mystical powers associated with them.
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High altitude lakes: often the brackish (slightly salty) Tso Moriri, Pangong Tso and Tso Kar (tso means lakes in Ladakhi) are said to be remnants of the ancient Tethys Sea. It is said they were formed when the tectonic plates collided and isolated little pockets of saltwater. Yet research publications are divided on this. Some still hold to the Tethyan origin and the formation of the lakes around 52 million years ago, whereas other studies have shown more recent, Quaternary (2.58 million years ago to date) processes at play.
As per the latter theory, these lakes were formed relatively recently, either in depressions formed during the Ice Ages, or when rivers were dammed or blocked by tectonic activity. The Pangong Tso for instance, might have been the result of several large earthquakes that caused a segment of the Pangong Tso river valley to be uplifted. As a result, the Pangong river was dammed, and without an outlet, filled up to form a lake. Tso Moriri is considered to have been formed during neotectonic activity - suture zones where tectonic activity continues, or is reactivated. Tso Kar may have been formed after the Ice Ages, in depressions left behind by glaciers.
*As always, I am indebted to Suvrat Kher (Rapid Uplift - a blog on geology, evolution and a changing planet) for his help with such complicated concepts. This section would have been a lot less lucid, and inaccurate without his inputs.
Another great resource for a deeper understanding of these landscapes, is Mike Searle's book, Colliding Continents mentioned in the reading section of this newsletter.
Beyond the formation, these high altitude salt lakes have also been a mainstay for cattle herders and nomadic traders in Ladakh. The native Pashmina and Cashmere goats, known as the Changthangi, are grazed regularly by the Changpa tribe along the lakes - the salt is essential for their development. Nomadic traders would mine the salt and carry it over the Zanskar range across Central India - where salt is a rare commodity, to trade it for other essentials. Along this former Silk (and Salt) Route, a shadow economy continues to date - China's recent One Belt-One Road also known as the Belt and Road initiative, hopes to formalize and broaden this economy. Though geopolitical analysts believe this is China's bid to extend its economic and political influence across Central and South Asia.
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Note: Ladakh's lakes (and the availability of water in these remote stretches), its mineral wealth, and its strategic location make it a hotbed for geopolitical activity - as the recent skirmishes along the Pangong in May 2020 attest. However, there's just that much I can cover in this newsletter. The book, Frontier Complex (mentioned in the recommended reading section) would be an interesting read on the geopolitics of this region.
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SUGGESTED READING (ARTICLES)
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Third Rock From the Sun: Exploring Ladakh with the NASA Crew
Kamakshi Ayyar
National Geographic Traveller India
A travel narrative on decoding the landscapes of Ladakh through the lens of geology.
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SUGGESTED READING (BOOKS)
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Colliding Continents - Mike Searle
What went into the formation of the Himalayas and the Karakorams, among the world's largest mountain ranges? How did the cataclysmic crash of the Indian plate into the Eurasian plate influence the geology of the region, and how does it continue to do so? In this book based on research and travel, Mike Searle tries to unlock the history of the tectonic upliftment, the deformation along the plate margins, and the metamorphism that has shaped and continues to shape the landscape.
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Ladakh: A Wanderer's Spectacle - Nabarun Bhattacharya
Ladakh is sometimes refered to as 'Shangri-La' - a mythical place that featured in James' Hilton's novel, Lost Horizon. While this epithet conjures up a sense of mythical awe, much like its landscapes, it has proven to be a detriment to the inhabitants of an otherwise desolate, harsh region. This is a sweeping narrative of the landscape and how it shapes the lives of the people living there, and the hardships they endure.
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Ladakh: Crossroads of High Asia - Janet Rizvi
This is one of the oldest, authoritative books on Ladakh, written in a scholarly vein covering history, people, cultures, environment and the politico-economic shifts of the region. What's more, the book has been revised several times since, and is a great reference for anyone interested in understanding the region from a broad, practical perspective.
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The Frontier Complex - Kyle J. Gardner
This book talks about both Ladakh's traditional role at the crossroads of Central India, and its changing political significance from the early days of the British Raj to the Aksai Chin War. What do such borderlands signify, and how have they (historically) shaped the identity of Ladakh and its people? Such questions also throw light on Ladakh's geopolitical significance today, as the full power of the modern state and its laws are brought to act upon the state.
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For the ebookworms:
Mountains of Central Asia Digital Dataset
This is a FANTASTIC, FREE collection of books, journals, maps and old photos related broadly to the Himalayas and its outlying ranges. This rich repository of rare, hard-to-find or expensive (think of bulky tomes!) reflects just how painstaking such a compilation must have been. All material can be downloaded for non-commercial purposes.
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Acknowledgements & credits:
Cover image: Ladakh. Suket Dedhia via Pixabay
Most section images & diagram: Devayani Khare
Tso Moriri lake: John Hill (CC BY-SA) via Wikimedia Commons
Reading section images: pulled from the article/book source. No infringement intended.
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