Quaternary system
Topic: Minerals, Rocks and the Rock Cycle · NCERT: Beyond NCERT
Meaning
The Quaternary system is India's youngest group of deposits, laid down in the last 2.6 million years. It is mostly loose material that has not yet hardened into rock. It includes the river alluvium (silt and sand left by rivers) of the north Indian plains, delta deposits, the wind-blown sands of the Thar Desert and the lake deposits of Kashmir called karewas. It has almost no economic minerals. Its real value lies in fertile soil and rich groundwater.
Example
The Indo-Gangetic–Brahmaputra plain is Quaternary alluvium. Older alluvium on higher ground is called bhangar, and newer alluvium on the floodplains is called khadar. In Kashmir, saffron is grown on the karewas.
Don't confuse with
- Tertiary system: the Tertiary is older (about 66–2.6 million years ago). It formed as the Himalaya rose, includes the Siwalik sediments, and holds petroleum and lignite. The Quaternary holds almost no minerals.