World's Oldest Mountain Range: Aravalli Formation Story
World's Oldest Mountain Range: Aravalli Formation Story
When the sun hadn't yet learned to shine in today's sky, when humans were nowhere to be found on Earth, even then a magnificent epic was being written in the soil of Rajasthan - the birth of the Aravalli mountain range.
Today, when you step foot on Rajasthan's land, beneath your feet lies 1.8 billion years of history buried deep. This is not merely a story of mountains, but a tale of Earth's childhood, of those days when continents were still searching for their place and oceans were dancing where deserts now spread.
The Proterozoic Era: Earth's Youthful Days
Approximately 2.5 billion years ago, when Earth entered its youth, the Proterozoic Era began. This was the time when oxygen first started appearing on Earth, and ancient life forms called stromatolites began flourishing in the oceans. In Rajasthan's Jhamerkotra, 1.8 billion-year-old stromatolites can still be found today, serving as witnesses to that ancient marine life.
The Rajasthan of that era was completely different from today's Rajasthan. There were no deserts here, nor the geography we see today. Instead, vast oceans stretched across this land, and sedimentary rocks and volcanic materials were accumulating on the ocean floor.
The Great Catastrophe: When Two Continents Collided
Phase One: Aravalli Craton vs. Bundelkhand Craton (1.8 Billion Years Ago)
1.8 billion years ago, an event occurred on Rajasthan's land that remains this region's defining characteristic to this day. At that time, the Indian subcontinent had three massive landmasses - the Aravalli Craton, Bundelkhand Craton, and Marwar Craton. These three approached from different directions and collided with each other.
First came the tremendous collision between the Aravalli Craton and Bundelkhand Craton. This collision was so powerful that the sediments and volcanic rocks accumulated on the ocean floor were thrust upward to form mountains. This process is called Orogeny (mountain building).
Banded Gneiss Complex: Rajasthan's Foundation Stone
During this catastrophic collision, the Banded Gneiss Complex (BGC) was formed. This is Rajasthan's oldest rock formation, older than 2.5 billion years. These rocks still contain remnants of that ancient ocean.
The BGC contains rocks like granite, gneiss, and amphibolite. These rocks indicate that conditions of extreme pressure and high temperature (approximately 600-800°C) existed here at that time.
Aravalli Supergroup: Birth of the First Mountain Range
Journey from Ocean Floor to Mountains
The period from 2 billion to 1.85 billion years ago was the era of Aravalli Supergroup formation. During this time, deposits of galena (lead sulfide) and other metals accumulated on the ocean floor. These can still be found in Rajasthan's Zawar mines today.
During this period, a rift valley formed in Rajasthan, where marine sediments and volcanic materials continued to accumulate. This process continued for approximately 200 million years.
Syn-Orogenic Granites: Strong Foundation of Mountains
When the two cratons collided, extreme pressure built up underground. This pressure melted rocks from Earth's deep layers, creating granitic magma. This magma rose upward and solidified to form syn-orogenic granites, which are 1.85 billion years old.
Thus, for the first time in Rajasthan, the Aravalli mountain range was born.
Delhi Supergroup: The Second Epic (1.7-1 Billion Years Ago)
Second Collision: Arrival of Marwar Craton
After the formation of the Aravalli mountains, there was peace for approximately 100 million years. Then, 1.7 billion years ago, another dramatic event occurred. The Marwar Craton came from the west and collided with the Aravalli-Bundelkhand Craton.
This second collision led to the formation of Delhi Supergroup rocks. These include strong quartzite rocks that form today's Delhi Ridge.
Western Margin Fault: Boundary Between Two Worlds
Between the two cratons, the Western Margin Fault formed, along with Phulad Ophiolite rocks. These rocks are remnants of that ancient ocean floor that lay between the two continents.
Geography and Environment of Ancient Rajasthan
What Was Rajasthan Like 1.8 Billion Years Ago?
The Rajasthan of that era was completely different from today's Rajasthan:
Geographical Position: Rajasthan was located near the equator at that time. It was part of the Pangaea supercontinent, surrounded by the Tethys Ocean.
Climate: It had a tropical climate. Temperature remained between 25-30°C. There were no distinct hot and cold seasons like today.
Marine Environment: All of Rajasthan was covered by shallow seas. These oceans were filled with carbonate reefs (limestone palaces) inhabited by ancient life forms like stromatolites.
Atmosphere: The atmosphere contained much less oxygen than today, but more carbon dioxide.
Early Signs of Life
Rajasthan's ancient rocks contain remains of cyanobacteria and green algae. These were the most primitive forms of life on Earth. The stromatolites found in Jhamerkotra are evidence that life existed here 1.8 billion years ago.
Geological Processes and Mineral Wealth
Metamorphism: Transformation of Rocks
During tectonic plate collision, extreme pressure and high temperature transformed original rocks into metamorphic rocks. This process created:
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Granite to gneiss
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Sandstone to quartzite
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Limestone to marble
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Shale to slate
Treasury of Mineral Wealth
During Aravalli mountain formation, various mineral deposits were formed in Rajasthan :
Base Metals: Lead-zinc at Zawar, zinc at Rampura-Agucha, copper at Khetri
Phosphate: Vast deposits of rock phosphate at Jhamerkotra
Mica, talc, asbestos: All formed during metamorphic processes
Aravalli Mountains: World's Oldest Mountain Range
World's Most Ancient Structure
The Aravalli mountain range is not just India's, but one of the oldest mountain ranges in the entire world. At 1.8 billion years old, it is 15 times older than the Himalayas.
Geographic Extent and Structure
Length: Approximately 800 kilometers (Gujarat to Delhi)
Width: Average 10-80 kilometers
Highest Peak: Guru Shikhar (Mount Abu) - 1,722 meters
Direction: Extends from southwest to northeast
Still a Living Mountain Range
Although the Aravallis are 1.8 billion years old, they are still tectonically active. Earthquake occurrences indicate that these mountains are still slowly growing.
Erosion and Time's Impact
Billions of Years of Wear
The Aravalli mountains were once taller than the Himalayas at the time of their formation, but billions of years of erosion have gradually worn them down. Rain, wind, and temperature changes have shaped these mountains into their current form.
Geological Evidence
Folded ridges near Udaipur still bear witness to that ancient tectonic activity. These structures show how ocean floor sediments transformed into mountains.
Modern Scientific Discoveries
Radiometric Dating
Modern U-Pb zircon dating techniques have revealed :
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Granite intrusions: 1.85 billion years old
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Metamorphism: 1.72 billion years old
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Second phase: 950-940 million years old
NASA Satellite Observations
NASA's Earth Observatory has recognized the Aravalli mountain range as "The Ancient Aravalli Range", calling it one of the world's oldest mountain ranges.
Rajasthan's Geological Heritage
Continuous Geological History
Rajasthan preserves continuous geological history from 3.5 billion years ago to today. This is rarely found anywhere else in the world.
Future Significance
The Aravalli mountains are not only Rajasthan's geographical backbone but are also extremely important for climate control, water conservation, and ecosystem management.
Conclusion: Immortal Tale of Earth's Childhood
When you look at Rajasthan's Aravalli hills, you're not just seeing stones, but 1.8 billion years of history. These mountains are witnesses to that time when continents were searching for their place, when oceans existed where deserts are today, and when life was in its most primitive form.
The collision of three massive cratons, transformation of ocean floor sediments into mountains, billions of years of erosion, and ongoing geological processes - all these together make the Aravalli mountains one of the world's oldest and most unique mountain ranges.
When stepping on Rajasthan's soil, remember that you're walking on Earth's childhood story - a story that is 1.8 billion years old and still being written today.
This is the true story of the Aravallis - not just of stones and mountains, but the great epic of time, patience, and nature's indomitable power.