How are they built on such deep waters? Why don’t they just float away?
In: Engineering
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They don’t float away because they aren’t boats. Boats float on top of the water, islands are essentially the tops of mountains (You are, in effect, standing on the top of a mountain that reaches all the way to the ocean floor and below), and while the water can carry off bits of sediments and generally erode the island, they generally can’t carry off the entire thing.
Now logically when you think of an artifical island you think of a boat structure, you know, they take something that floats, and stack things on top of them. However as I mentioned, that’s not how islands work. If you pour sand into the ocean, it’ll float to the ocean floor, and if you just built a boat and moor it then it could float away, or sink, or whatever.
What is usually done is essentially stack a bunch of rocks or cement on the ocean floor, and then pour a bunch of sand, cement, soil, or whatever on top of that to serve as the foundation of a new island.
Other methods also exist. The dutch have invented a method where they build a dyke around the area they want to reclaim from the ocean, and then pump the water out, using the old ocean floor as their new land island.
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