Purana Rock System
(600 to 1400 million years ago)
Imagine a vast, ancient landscape where mighty rivers deposited layers of sand and clay over billions of years. These layers solidified into rock, forming some of the most recognizable geological formations of India. This is the Purana Rock System, a transition between the ancient Archaean rocks and the younger, more fossil-rich formations that came later.
What is the Purana Rock System?
📍 Age: Formed after the Archaean era but before the Dravidian rocks.
📍 Formation: Sedimentary deposits that settled over the older Archaean basement.
📍 Significance: Important for minerals, building materials, and historical landmarks.
This system is divided into two major groups:
- Cuddapah System (Older)
- Vindhyan System (Younger)
Cuddapah System
📍 Location: Found in Cuddapah district of Andhra Pradesh, extending into parts of Telangana, Odisha, and Chhattisgarh.
📍 Formation: Formed in synclinal basins (large depressions between mountain folds where sediments accumulated over time).
🔹 Key Features:
- Composed of unfossiliferous clay, slates, sandstones, and limestones.
- Best outcrops (rock formations visible at the surface) are seen in Cuddapah district, Andhra Pradesh.
- Rich in iron, manganese, copper, cobalt, and nickel—important for the mining industry.
- Contains large deposits of cement-grade limestone, essential for construction and infrastructure.
💡 Ever wondered where the raw materials for your house’s cement and iron framework come from? There’s a high chance they originated from Cuddapah rocks!
Vindhyan System
📍 Location: Spreads across Madhya Pradesh, Uttar Pradesh, Rajasthan, Chhattisgarh, and Bihar.
📍 Formation: Thick layers of sedimentary rocks (up to 4000 m thick) laid over the Archaean base.
🔹 Key Features:
- Named after the Vindhyan mountain range, which is shaped by these rocks.
- Composed of sandstones, limestones, and shales.
- Mostly unfossiliferous, meaning no evidence of ancient life.
- Partly covered by the Deccan Traps, a later volcanic formation.
- Famous for diamond-bearing regions, especially in Panna (Madhya Pradesh) and Golconda (Telangana).
- Though it lacks metal ores, it provides durable stones, ornamental stones, limestone, and pure glassmaking sand.
🏆 Economic Importance:
- The Panna diamond mines in Madhya Pradesh were once among the world’s richest sources of diamonds.
- Red sandstone from the Vindhyan system was used to build historical monuments like the Red Fort and Fatehpur Sikri.
💎 A Diamond Connection: The legendary Kohinoor diamond, one of the world’s most famous gems, is believed to have come from Golconda, a Vindhyan formation.
Conclusion
The Purana Rock System acts as a bridge between the ancient Archaean rocks and the more recent Dravidian formations. While the Cuddapah system fuels India’s mining and construction industry, the Vindhyan system has left a lasting mark on history through its diamonds and sandstone-built monuments.
