how long does it take an island to develop?

Question

I'm writing a novel where the characters go to a school on "Atlantic Coast Islands", a made-up island. However, what I want to know is how long it takes an island to develop.

Answer 1

If you want a realistic scenario for your island, you have to consider what types of islands are likely to develop in your setting, the Atlantic Coast. For my response, I will assume your focus is on the Atlantic Coast of North America.

Some examples of real islands near the coast are Martha's Vineyard and Nantucket in Massachussets, Long Island in New York, and several major barrier islands along the coastlines of New Jersey, Delaware, Virginia, and North Carolina.

The time period over which these islands developed depends mainly on the processes involved. The two key processes for islands along the Atlantic coast are changes in sea level which exposes high elevation terrain as islands (such as Long Island or Nantucket), and deposition (of sand, such as in the barrier islands). Its reasonable to set the starting point for the development of the islands visible today as the end of the last ice age, 18,000 years ago. The processes have occured slowly since then, but on the time scale of Earth history (geologic time) its pretty quick.

For more information on the development of the Atlantic coastal islands, especially the barrier islands, this is a good source: http://ncnatural.com/Coast/dynamics.html

Answer 2

I believe that an island came up off the coast of Greenland in the 19th century. As it was caused by volcanic action it took only days to appear. Unfortunately it went back into the ocean again after a short period of time.

Answer 3

Volcanic islands can literally develop overnight. Other islands can develop from larger islands due to storms cutting through them.