The Bahamas was formed like most of the world volcanically. So, The Bahamas crust is made primarily by igneous sedimentary rocks (i.e. limestone).
The Island of the Bahamas is the highest point of underwater banks. 
(Photo credited by Ronda Cox
Some of the Bahamas island land is made up of the remains of coral reefs (Attrill, 2000). The word Bahamas actually means shallows seas. In the Bahamas one could be swimming or sailing in 20 feet of water and in a flash it can quickly become only 6 feet of water. The Bahamas is land that was once under sea and was pushed up during Plate tectonics and Shallow water. The Island of the Bahamas used to be part of the west coast of Africa, but moved away due to Plate Tectonics approximately 300 million years ago.
(Photo credited by Geology.com)
Works Cited
Attrill, R. (2000, ). Rod Atrill's Bahama Wildlife. Retrieved April 22, 2011, from Rod Atrill's Bahama Wildlife: http://www.motygido.co.uk/bahamas_birthplace.htm
