I’ve been reading Bill Bryson’s a short history of nearly everything. This post is composed of quotes from the book.
It’s answered some questions. For example, how many continents are there?
Answer- your question makes no sense, you’re referring to bits of land that stick out over the water but you haven’t specified the size to differentiate a continent from an island.
The correct answer is Plate Tectonics. This is what made the mountains, it is why you get sea creature fossils at the top of mountains and it is why the Earth is not just a round ball completely covered in water.
If the Earth were perfectly smooth, it would be covered everywhere with water to a depth of 4 kilometres. There might be life in that ocean, but there certainly wouldn’t be humans.
Well into the 1970s, one of the most popular and influential geological textbooks, The Earth by the venerable Harold Jeffreys, strenuously insisted that plate tectonics was a physical impossibility, just as it had in the first edition way back in 1924.
Iceland is split down the middle, which makes it tectonically half American and half European. New Zealand, meanwhile, is part of the immense Indian Ocean plate even though it is nowhere near the Indian Ocean.
It is thought – though it is really nothing more than a thought – that tectonics is an important part of the planet’s organic well-being. As the physicist and writer James Trefil has put it, ‘It would be hard to believe that the continuous movement of tectonic plates has no effect on the development of life on earth.’ He suggests that the challenges induced by tectonics – changes in climate, for instance – were an important spur to the development of intelligence.