What is the evidence for sea-floor spreading / plate tectonics?
• Continental fit The east coast of South America and the west coast of Africa fit together with very few gaps. • Common geology Rare Devonian violet quartzites are found in parts of Brazil and South Africa. These areas would have been adjacent when the two continents were joined. • Flora and fauna fossil record Similar fossil remains may be found in both the Americas and in Africa and must therefore share a common descent; the distances separating them preclude migration as an explanation. For instance, remains of Lystrosaurus, a sheep-sized reptile that lived around 200 million years ago, are found throughout all of the southern continents. • Palaeomagnetic explanation The earth’s magnetic polarity has reversed in the past and the parallel magnetic “striping” of sections of sea-floor either side of the mid-Atlantic ridge allows dates to be compared. The basaltic ocean floor also ages with increasing distance from the ridge in either direction, further suggesting that the floor is spr
