Continental Drift Theory by Wegener

Continental Drift Theory of Wegener:

             Alfred Wegener, a German Climatologist, published the continental Drift Theory in 1912.  It came in light in 1922 in a book titled, " Die Entstehung der Kontinente and Ozeane" which was translate in English language in 1924 named as " The Origin of Continents and Oceans".

Assumptions:

(i). Continental mass was made up of SiAl.

(ii). Oceanic crust was made up of SiMa.

(iii). SiAl floated over SiMa with minimum resistance between them.

(iv). There was a huge united landmass named Pangea in Carboniferous  period and it was surrounded by a huge water body called Panthalassa (Panthalassa was considered as a primative form of Pacific Ocean).

Description of the Process of Continental Drift Theory by Wegener:

            According to Wegener, the main forces responsible for the movement of Continental landmasses were bouyancy force, differential gravitational forces and tidal force.

* The continental landmasses, floating over the oceanic crust moved in two directions towards the Equator and Westward. Equator ward movement was under buoyancy and differential gravitational force. The West ward movement was under tidal force.

* Pangea landmass was broken latitudinally into two parts namely Angaraland and Gondwanaland respectively. Northern part was known as Angaraland and Southern part was known as Gondwanaland. The intervening spaces between these two landmasses came to be known as "Tethys Sea"

* Gondwanaland, during Cretaceous period, split into Indian peninsula, Madagascar, Australia, Antarctica, Africa and South America.

* Angaraland split into two continents, namely North America and Eurasia.

* Similarly, Oceans were formed , The S shape of Atlantic is due to differential movement of North and South America. Indian Ocean was formed due to Northward movement of Indian peninsula. Remaing portion of Tethys became Mediterranean sea. Arctic was formed due to movement of Continental blocks towards North pole.

* Wegener also described the origin of fold mountains. He stated that the frontal edges of Westwards drifting continental blacks of North and South America were folded against oceanic crust and Rockies and Andes were formed. Similarly, Alpine ranges were formed due to Equator ward movement.