How do reefs become part of the land above water?

Answer 1

There are a couple of ways it could happen. In an ice age, for instance, more of the water on the earth could be frozen up in glaciers and ice caps, leaving ocean levels lower and reefs exposed.

The land under the coral reef could be uplifted somehow. One way that could happen is if an oceanic plate is sliding under the continental plate the reef is on. Another way is if continents collide, as with the collisions of North America, Europe, and Africa that caused the Appalachian mountains to form.

If you think about it, anytime you've got limestone above ground, that's probably a really old coral reef , so it happens quite often.

There are exposed reefs where I live, and now I've got to figure out why!

Answer 2

Coral reef atolls form when a volcano raises of the ocean floor, builds up a little island and the heat attracts coral to grow. After a period of inactivity, the dirt of the island erodes away leaving the reef.