Future of the Virgin Islands

The Virgin Islands contain a distinctive type of physical geography. The Islands were created some 100 million years ago (Belarus and Luck) due to plate tectonics and the subduction of the Caribbean plate under the North American plate. Due to its location in near the equator the Virgin Islands are tropical islands with high humidity.

The Virgin Islands are prone to rapidly changing physical geography due to impacts from the ocean. The littoral zone or coastal region of the islands is steadily shifting every day. At first the Virgin Islands were just solidified magma pushed out of the ocean. The Virgin Islands were not always sandy beaches but solid igneous rock jutting out of the ocean. Tides have taken their toll on the islands, weathering the rock and changing the formation of their sea cliffs.  There is evidence of this erosion in the sea cliff notches that from on the bottom of the sea cliffs. This encourages mass wasting as the cliff becomes less able to support the upper shelves until a storm comes and causes mass wasting. Then the process starts again with the new cliff line.

Notched Cliff on Jost Van Dyke

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1,000 Years

In 1,000 years the littoral zones will be made up of less igneous rock and consist of larger sandy shores. The islands will become further submerged in the ocean through natural degradation due to storms and erosion.  The shore current will shift the shoreline with swash and backwash. Due to the shallow waters in that region the majority of the waves are spilling breakers, where there is minimal change in sea floor grade. The steeper the grade the larger the waves will oscillate creating a quicker physical change.

10,000 Years

As the ocean continues to impact the land form of the Virgin Islands in 10,000 years the rocky shore lines will be depleted into smooth sandy beaches. The likelihood of this happening is already evident by the formation of tombolos and lagoons on some of the islands. As waves refract around islands and formation in the ocean they meet on the opposing side pushing sand together creating a sand bridge between islands.  Many of the island shore lines are beginning to in both the British and American side of the islands has a shift in physical geography from sandy coasts to rocky sea cliffs on the leeward side.

 

Trombolo off of St. Thomas

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100,000 Years

In 100,000 years as the wave degrade the coastal structure of the islands a new factor will affect the physical geography of the Virgin Islands, rising sea levels. The earth has always gone through cycles of ice ages as glaciers accumulate and ablate.  In the next 100,000 years the shifting of the water levels will cause the further erosion. While the cliff notches of today’s islands seem minuscule the rising water levels will allow sea tides to affect a greater area. Then when the water level decreases again the ocean floor will be emerged and turned to vegetation.

Starting as islands surrounded by cliffs the Virgin Island’s Littoral shifts will determine the future of its physical geography. From its volcanic origins the future of this tropical oasis is still undetermined. However, the ocean will naturally regulate the coast and shift the islands from cliff structures into a smooth sandy coastal system.

"GEOLOGY OF THE VIRGIN ISLANDS." BCRC Home. Web. 09 June 2010.
<http://bcrc.bio.umass.edu/vifishandwildlife/Education/AquaticEd/Coloringbook/EnvColorBook/UsedFiles/Geology.
htm>.

Luck, Tamara, and Lauren Baltrus. "Virgin Islands." Earth Science in our National Parks. Tangient LLC, 09 2010. Web. 6 Dec 2012. <https://earthscience-in-the-nationalparks.wikispaces.com/Virgin Islands>.