Major plates
Topic: Continental Drift, Sea-floor Spreading and Plate Tectonics · NCERT: Class 11, Ch 4 "Distribution of Oceans and Continents"
Meaning
The lithosphere is the earth's rigid outer shell, made of the crust plus the top of the mantle. It is broken into large slabs called plates. NCERT lists seven major plates:
- Antarctica and the surrounding ocean
- North American, with the western Atlantic floor
- South American, separated from the North American plate along the Caribbean islands
- Pacific
- India-Australia-New Zealand
- Africa, with the eastern Atlantic floor
- Eurasia and the adjacent ocean
These plates are bounded by young fold mountains, ocean trenches and/or faults. Each plate moves as one rigid unit over the soft asthenosphere below, usually a few centimetres a year. The Pacific plate is the largest, and it is almost entirely oceanic.
Example
The India-Australia-New Zealand plate carries Peninsular India. Its northern edge is pushing into the Eurasian plate at the Himalayas, which is why the Himalayas are still rising.
Don't confuse with
- Minor plates: NCERT's minor plates are Cocos, Nazca, Arabian, Philippine and Caroline. "Antarctica is a minor plate" is false.