4 ms·

The main deposit is sand, as I understand it. That's why atolls change shape a lot. On the whole, they're not even as stable as coral. Building (with paving) is

• dredmorbius 11y ago
  My understanding is seamount (underwater volcano) on which coral builds further toward the surface, from depths of < 200' (~60m), topped with sand which is almost certainly formed from coral. The sand topping will blow way in wind, but with slow sea rise, coral can build up. Coral cannot grow above sea level, so atolls are of necessity close to sea level. With rapid rise, particularly where coral growth is retarded (carbonate levels, other forms of coral blight), you'll lose that ability entirely, and the island will flood. More: https://en.wikipedia.org/wiki/Atoll https://en.wikipedia.org/wiki/Atoll
  • 23452436 11y ago
    Correct. Atolls (the bit above water) are mainly sand, regardless of the sand's origin. Not a good place to build.