Anyone who’s been to the geology section of a science museum may have had the opportunity to put together a jigsaw puzzle of the continents, fitting Africa to South America, twisting North America against Europe and so on.
It isn’t just a game: though many people may not realise it, the position of the continents on the Earth’s surface is important.
The continents affect heat transport by the ocean and have a part to play in influencing the formation of ice.
By understanding their former positions and rates of movement, we can increase our understanding of the whole earth system – but how can we tell where the continents were in the past?
Continents and Supercontinents
The theory of continental drift is now well established: We know that supercontinents form, break apart and reform.
The lines of ancient collisions – sometimes by continuous accretion of island arcs or slivers of land, sometimes in mighty clashes of continents – can be identified by geological features such as mountain chains and even mineral seams (the rich Mother Lode of Californian Gold Rush fame marks the line of such a collision). However, identifying the positions of former continents is a little more problematic.
You’ve only to look at the corresponding coastlines of western Africa and eastern North American to see where these two continents broke apart. Not all pieces of our jigsaw fit together so easily, however.