Essay - Theory of continental drift

Q. Discuss the theory of continental drift

• Associated with German meteorologist, Alfred Wegener

• He first published the theory in 1912.

• He suggested all continents were once combined in a super continent known as Pangea.

• He proposed that this single land mass was surrounded by one massive ocean called Panthalassa

• He believed that approximately 200 MYA, Pangea broke in half

• One land mass (Laurasia) consisted of modern day Europe N America and most of Asia (Northern hemisphere)

• The other land mass (Gondwanaland) consisted of S America, Africa, India, Australia & Antarctica (Southern hemisphere)

• Separated by the Tethys Sea

• He claimed that since then, Laurasia and Gondwanaland have continued to fragment further and further to form the current day land masses.

• He implied that colliding continents were the cause of rock folding into mountain ranges (this was his only flaw) It has since been proven that the movement and collision of plates causes this

• His ideas were first rejected by the geologists and scientists of the time

• His theory was accepted in 1963, 36 years after his death.

• This is because it was discovered that the Mid Atlantic Ridge was part of a volcanic submarine mountain range

• This provided evidence of the ocean floors spreading apart

• Proofs of continental drift:

• - Continental fit (Coastlines of continents appear to look as though, if pushes back together, would fit like jigsaw)

• - Matching fossils (Comparable fossils have been found in the precise locations, mainly coastlines, where Wegener believed the continents were once joined)

• - Matching rocks and mountain ranges (mountain ranges appear to end on one edge of a land mass and recommence on the opposing edge of a neighbouring land mass. Many are identical in age, structure, and rock type)