Geography Quiz: Continental Drift and Plate Tectonics

Wegener, a German meteorologist and climatologist, put forward the continental drift theory in 1912 and developed it in his book The Origin of Continents and Oceans; he argued that all the continents once formed a single landmass, Pangaea, which broke up about two hundred million years ago.

Wegener held that about two hundred and fifty million years ago all the land of the earth lay together as one mass, Pangaea, and that one enormous ocean, Panthalassa, surrounded it.

Wegener attributed the horizontal movement of the continents to the pole-fleeing force, which arises from the rotation of the earth and the bulge of the equator, and to the tidal force, which arises from the attraction of the moon and the sun.

When Pangaea began to break about two hundred million years ago, it parted into a northern mass called Laurasia or Angaraland and a southern mass called Gondwanaland, and the long narrow Tethys Sea lay between the two.

After the detailed mapping of the ocean floor during and after the Second World War revealed mid-oceanic ridges, deep trenches and a surprisingly thin cover of sediment, Hess proposed in 1961 that molten material rises along the ridge, forms new ocean floor and pushes the older floor away on both…

The Indian plate moved northwards and met the Eurasian plate. Both carry light continental crust, so neither could sink far into the mantle; instead the sediments of the Tethys Sea lying between them were compressed, folded and thrust upwards to form the Himalaya, and the collision is still going on…

Along the San Andreas Fault the Pacific plate and the North American plate slide horizontally past each other.

It lies between South America and the Pacific plate and is one of the well known minor plates, along with the Cocos, Arabian, Philippine, Caribbean, Juan de Fuca, Scotia, Caroline and Fuji plates.

Near Easter Island in the South Pacific the rise spreads at more than fifteen centimetres a year, the highest rate measured, while the Arctic Ridge in option A has the slowest rate of less than two and a half centimetres a year.

Plate tectonics, propounded in 1967, holds that the lithosphere is broken into seven major plates and a number of minor ones that move over the plastic asthenosphere.

The crust is the outermost and thinnest layer of the earth and is of two kinds. The continental crust, made largely of lighter granitic rock rich in silica and aluminium, averages about thirty kilometres in thickness and reaches about seventy kilometres under young fold mountains such as the Himalaya.