Forces of Drifting
The continents do not move on their own. Their slow drifting is caused by powerful forces coming from inside the Earth’s interior, especially from the mantle layer below the crust.
1) Convection Currents:
The mantle is extremely hot, almost molten rocky material. It is constantly undergoing circular motions called convection currents, similar to how water circulates when heated in a pot.
As the hot mantle material rises and colder material sinks, it generates huge forces that cause the continents above to move and drift across the Earth’s surface over millions of years.
2) Seafloor Spreading:
At the mid-ocean ridges, the hot molten rock rises from deep inside the mantle, forming a new oceanic crust that pushes the existing crustal plates apart.
As new crust is generated, it forces the attached continents on either side to drift further away from each other in opposite directions.
3) Slab Pull:
At some plate boundaries, one tectonic plate gets pulled down or subducted under another plate. This “slab pull” force can also drag the attached continents along, causing them to shift slowly over long periods.
4) Mantle Plumes:
Narrow streams of hot rising mantle material called “mantle plumes” can push up the crust and slowly move continents from below over vast time scales.
Distribution of Oceans and Continents| Class 11 Geography Notes
The theory of continental drift proposes that the continents on Earth’s surface have slowly moved and drifted across the planet over millions of years. This is caused by powerful forces originating from within the Earth’s interior, especially the convection currents in the mantle layer below the crust. The drifting and rearranging of continents over time has shaped the distribution of landmasses, oceans, climates, and life forms we see today.
Let us learn more about the distribution of oceans and continents!
Distribution of Oceans and Continents| Class 11 Geography Notes