Kutch or Kachchh (as it is sometimes spelt), is a perfect example of a tectonically controlled landscape overlaid with sedimentary deposits. It has features like salt pan expanses (Little Rann and Great Rann), low-lying banni grasslands with its semi-nomadic cattle herders, hilly regions of alternating sandstone-shale bands, and the southern coastal plains with Mandvi and Mundra ports.
To better understand Kutch's landscape, we need to brush up on some school geography terms: fault lines, horst-and-graben, and rift basins.
Fault Lines: the fractures along which the Earth's tectonic plates move. Earthquakes usually (but not always) occur along fault lines.
Horst-and-Graben (range-and-valley): a topography of alternating raised and lowered blocks created by parallel fault lines that dip in different directions (up and down). The raised block is known as a horst or range and can form plateaux, mountains or ridges. The lowered block is known as a graben, which may form low-lying basins and rift valleys.
Rift basin: a depression created by faults on one (half-graben) or both sides (graben), where over time river channels deposit sediments.
Kutch's landscape was shaped by two major tectonic events and as a result of several major and minor faults. It comprises several horsts - like the Kala Dungar, or Katrol Hills, and grabens or lowlands like the plains and salt marshes. The lowlands are characterised by sediment deposits like alluvium (from rivers) or mud or salt, laid down between 2.5 million years and continue to date.
RANN OF KUTCH: GREAT & LITTLE
The incredible colour gradients of the Rann of Kutch.
Image credit: Khyati_Studios/9 Images via Pixabay
The most distinct features in the Kutch region are the two low-lying saline marshes - the Great Rann (~15,000 sq. km) and the Little Rann (~4,000 sq. km). Rising no more than 3-5 metres above sea level, the salt-encrusted ranns remain dry for the most part of the year, except for the monsoons.
To the surprise of first-time visitors (like it was for me), the Rann is not just white - subtle shades of violet, purple, and pink tint the surface, as the vast expanse of salt flats stretches out to the horizon. It is a mesmerising sight, sometimes shimmering with mirages - much like in a desert. There are several pipelines that run parallel to the road across the salt pans - some which continue to carry water into the arid heart of the Rann, others that have been claimed and clogged by salt crystals. One can tell the difference between the two, as water pools in myriad hues at the base of the active pipelines.
Geologically, the Rann was once a shallow part of the Arabian Sea which was uplifted by tectonic activity and subsequently, isolated. In the time of Alexander of Macedonia (~330 BC), the Rann was documented as a navigable lake, with the river Ghaggar still emptying into it. Since then, the Ghaggar has been hijacked by the Indus and Ganges - its ancient channels are still faintly visible along the northern margins of the Rann. The Luni River continues to drain into the rann, and along with some other rivers, forms a delta that ends in the Kori creek.
DHOLAVIRA: A HARAPPAN CITY
As you traverse the Great Rann, four distinct islands namely Pachham, Khadir, Bela and Chorar, appear over the horizon - seeming almost like a mirage in this desolate expanse of salt and sand. This East-to-West chain of islands (bet in Hindi) formed along a fault line, once rose above the Arabian Sea when the region was inundated. These landmasses are highlands today, in comparison to the salt marshes.
Of all the islands, the Khadir bet is the most fascinating - after all, an Indus Valley city has been unearthed there.
Dholavira - A Harappan site: considered among the five largest Harappan excavations, and the most significant archaeological site to have been discovered in India, Dholavira has provided us fresh insights into the Indus Valley civilisation. In July 2021, the site was listed as a UNESCO World Heritage site.
Dholavira, with its fascinating water conservation system - rain-fed reservoirs, drains, tanks, step-wells, and a dam over a seasonal stream, is testimony to the ingenuity and resilience of its desert-dwelling people. Terracotta seals, pottery shards, jewellery, a doorframe bearing 10 characters from the Indus script, and funerary structures among other findings, mean that the secrets of this ancient civilisation are still waiting to be unlocked.
To me, the most exciting discovery was that of a fault line running through the rainwater channels - hinting at a possible theory on how the civilisation might have declined or dissipated.
VIDEO RESOURCE
Prof. Shereen Ratnagar: counter-argument on climate change as a theory for the decline of the Indus Valley civilisation by examining the ingenious water storage systems found at Dholavira.
This is a thorough ~45-minute analysis.
FOSSIL PARKS & BEDS
A petrified tree at Dholavira Fossil Park Image credits: Nagarjun Kandukuru via Wikimedia Commons, CC-BY.
Dholavira Fossil Park: the fossil park near Dholavira lies close to the India-Pakistan border. Despite its small area, the park boasts some petrified logs and dinosaur eggs just metres away from the salty stretches of the Rann of Kutch.
You can also find fossils of ancient marine creatures like foraminifera, trilobites, ammonites, molluscs and other shelled creatures in the limestone beds around Kutch. The Kas Dungar, Khatrol Hill, and Kuar Bet have yielded some interesting specimens of dinosaurs, dinosaur eggs, and crocodile eggs, among other vertebrates.
Other fossil remains of megafauna - ancestors of crocodiles, rhinos, boars, sea cows, and giraffes, are still being analysed. In 2018, the Sivapithecus - an 11 million-year-old hominid (ape) was also found in the Kutch region - marking it as the oldest such fossil to be found so far south along the Indian peninsula. In 2019, a publication detailed how 14 million-year-old fossils in the Kutch region give evidence of this now-arid area being a green, forested expanse rich in biodiversity.
Kutch is a geologist's dream - where one can marvel at both tectonic and sedimentary processes. As Kutch becomes a popular destination for its culture, history, art, handicrafts, and biodiversity (wild asses and winter migrant birds!), I hope its geological legacy can be explored in more intrepid ways than as dull, dusty museum relics.