Convection Current Theory help us to understand concept of Seafloor Spreading and Plate tectonics theory.
Post Drift Studies
A number of discoveries during the post-war period added new information to geological literature. Most of the evidences for the continental drift theory of Alfred Wegener were collected from the continental areas. New literature collected from the ocean floor mapping provided new dimensions for the study of distribution of oceans and continents.
You can also check – Geography Notes for UPSC
Convection Current Theory / Convectional Current Theory
While explaining the processes of mountain building, Arthur Holmes put forward his theory of convection current in 1928-29.
- According to Holmes, convection currents exist in the mantle portion of the Earth.
- The cause of the origin of these currents is the presence of radioactive elements which causes thermal differences in the mantle portion.
- According to this theory, the intense heat generated by radioactive substances in the mantle (100-2900 km below the earth surface) seeks a path to escape and gives rise to the formation of convection currents in the mantle.
- Wherever rising limbs of these currents meet, oceanic ridges are formed on the seafloor due to the divergence of the lithospheric plates (tectonic plates), and wherever the failing limbs meet, trenches are formed due to the convergence of the lithospheric plates (tectonic plates).
- Wherever rising limbs of these currents meet, oceanic ridges are formed on the seafloor due to the divergence of the lithospheric plates (tectonic plates), and wherever the failing limbs meet, trenches are formed due to the convergence of the lithospheric plates (tectonic plates).
- This was an attempt to provide an explanation to the issue of force, on the basis of which contemporary scientists discarded the continental drift theory.
Convection Cell
The plate movements are caused by the convection cells. Convection cell is the circulation of the molten materials caused by the heat derived from the core.
How and why plates move in different directions?
When the molten materials( magma) circulate in different directions, they push or pull the plates in different directions. Thus, the plates move towards each other, move away from one another and move side by side. The plate movements cause the formation of fold, fault, earthquake, and volcano to occur.
Criticism of Convectional Current Theory
- The entire process of convection currents is based on heat generated by radioactive materials in the substratum (now mantle), however numerous scientists have questioned whether the needed amount of heat generated by radioactive elements is available.
- Convective currents may not be formed if heat is insufficient, and so the entire mechanism and working of the theory will be impossible.
- It’s also worth noting that rising currents condense their heat into the crust. This process also results in heat loss, which could cause currents to weaken.
- Because of a lack of heat to generate these currents, the horizontal flow of thermal convection currents beneath the continental and oceanic crusts is likewise a dubious phenomenon.
- If the convergent movement of convective currents cannot flow horizontally, the descending column will not exist, and the mountain will not develop.
Convectional Current Theory UPSC
Question can be asked in the UPSC based on distribution of Ocean and Continent, Theory of Continental Drift, Plate tectonics theory and Seafloor spreading theory but theory of convection current help you in the understanding of seafloor spreading and Plate tectonics.