How Were The Caribbean Islands Formed?

The Caribbean islands are fascinating and mysterious land formations that attract people from all over the world for their beauty and exploration opportunities.  We know the Caribbean islands didn’t pop out of nowhere so where did they come from? As an avid traveler of the Caribbean region I’ve often wondered the same thing, so, I set out on an amazing investigative journey to find out how the Caribbean islands were formed and I’d like to share my findings with you.

The largest group of the Caribbean Islands were formed by volcanoes erupting from the ocean floor while many other islands broke off the North American continent millions of years ago. Several of the smaller islands are a result of coral buildup peeking through the ocean’s surface. 

The Caribbean Islands cover an area of 90,000 square miles and consist of three main island groups including The Bahamas, The Greater Antilles and The Lesser Antilles

Most islands in each island group were formed in the same way while smaller islands within the group may have been formed differently or by more than one island formation process

How Exactly Were The Caribbean Islands Formed?

Scientists have established a classification system based on the way the island was formed. Within this system, there are five types, including:

  1. Continental Islands
  2. Tectonic Islands
  3. Volcanic Islands
  4. Coral Islands
  5. Barrier Islands

The Caribbean Islands are either a Continental, Tectonic, Volcanic or Coral formation type. Let’s explore each island formation type in more detail.

How Continental Islands were formed

Continental islands were once connected to a continent and were separated from the continent. Separation took millions of years and occurred in one of 2 ways

  1. The sea-level rose around the portion of the mainland that eventually became the island (i.e. due to melting glaciers)
  2. The portion of land that linked the mainland and the would-be island was eroded by rivers, lakes and ocean waves

The islands in the Greater Antilles island group are an example of continental islands. This includes:

  • Cayman Islands
  • Cuba
  • Hispaniola (where the nations of the Dominican Republic & Haiti reside)
  • Jamaica
  • Puerto Rico

These Caribbean Islands were thought to have been originally part of North America and separated over millions of years through erosion by rivers, lakes and ocean waves. 

The Bahamas are also an example of Continental islands.

Although not part of the Caribbean Island chain, Great Britain and Ireland are also continental islands, formed by breaking off from Europe over 10,000 years ago.

how Volcanic islands were formed

Volcanic Islands – sometimes referred to as “oceanic”- are formed when an oceanic volcanic erupts then builds up lava and ash. In most cases, this happens after the volcano erupts many, many times. 

Most of the Lesser Antilles were formed this way including the following Caribbean islands

  • Anguilla
  • Antigua and Barbuda
  • Aruba
  • Bonaire
  • Curacao
  • Dominica
  • Grenada
  • Guadeloupe
  • Martinique
  • Montserrat
  • Saba
  • St. Barthelemy
  • St. Eustatius
  • St. Kitts & Nevis
  • St. Lucia
  • St. Maarten
  • St. Martin
  • St. Vincent & The Grenadines
  • The US Virgin Islands
  • The British Virgin Islands.

Although not part of the Caribbean Island chain, Hawaii and Japan were also formed by underwater volcanoes

how Tectonic Islands were formed

Tectonically formed islands are created as a result of material build-up from the earth’s plates scraping against one another. When the plates bump into one another, one pushes on top and soil, rocks and other materials get scraped and piled up to the point where they form a landmass. It takes millions of years for enough buildup to form an island.

Barbados is one of the Lesser Antilles island groups thought to have formed tectonically as well as via coral build-up which we’ll discuss next.

how Coral islands were formed

Coral islands are low, flat islands comprised mostly of coral reefs. Coral reefs are limestone formations composed of tiny sea organisms and their remains they leave behind when they die. Coral growth thrives in warm, shallow water. 

Sometimes the coral grows around the top of a volcanic island as the sea level rises around it, other times as an island sinks. Eventually, after the coral builds up enough and after many volcanic eruptions push the coral buildup upward exceeding the sea level, an island is created.

Caribbean islands that are formed primarily via the coral process include the Florida Keys and Barbados. (Barbados is an island formed by more than one island formation process as mentioned earlier).

how Barrier Islands were formed

None of the Caribbean Islands were thought to have formed this way but it may interest you to know these types of islands are comprised of sediment (sand, silt, and gravel).

Rivers and streams bring the sediment to the seashore and ocean waves along with winds begin to carve ridges and edges alongside the shoreline resulting in barrier islands.

The Outerbanks in North Carolina and Padre Island in Texas are examples of barrier islands.

The table below details the Caribbean Islands and formation type they fall into.

Island Island Formation Typ
Anguilla Volcanic
Antigua and Barbuda Volcanic
Aruba Volcanic
Barbados Tectonically
Bonaire Volcanic
Cayman Islands Continental
Cuba Continental
Curacao Volcanic
Dominica Volcanic
Florida Keys Coral
Grenada Volcanic
Guadeloupe Volcanic
Hispaniola Continental
Hispaniola Continental
Jamaica Continental
Martinique Volcanic
Montserrat Volcanic
Puerto Rico Continental
Saba Volcanic
St. Barthelemy Volcanic
St. Eustatius Volcanic
St. Kitts & Nevis Volcanic
St. Lucia Volcanic
St. Maarten Volcanic
St. Martin Volcanic
St. Vincent & The Grenadines Volcanic
The Bahamas
Continental
Trinidad and Tobago Continental
Turks and Caicos Islands Continental
Virgin Islands, British Volcanic
Virgin Islands, United States Volcanic

Caribbean islands formed by volcanoes & Volcanic Eruptions

Considering the largest islands in the Caribbean were formed from volcanoes you may be wondering if they’re active and if any have erupted.

According to CaribbeanVolcanoes.com, the Caribbean Islands with potentially active volcanoes include:

  • Saba
  • St. Eustatius
  • St. Kitts
  • Nevis
  • Montserrat
  • Guadeloupe
  • Dominica
  • Martinique
  • St. Lucia
  • St. Vincent
  • Grenadines
  • Grenada

The last volcano to erupt in the Caribbean was the Soufriere Hills volcano of Montserrat which erupted in 1995.

According to the University of the West Indies below are the Caribbean Island Volcano Eruptions in the last 300 years.

Volcano / Island Year
Soufriere (St. Vincent) 1718
Soufriere (St. Vincent) 1812
Soufriere (St. Vincent) 1902
Mt Pelé (Martinique) 1902
Soufriere (Guadeloupe) 1976 – 77
Soufriere (St. Vincent) 1979
Soufriere Hills (Montserrat) 1995

It isn’t possible to know when every volcano on earth will erupt next, if ever. Each volcano is like a person, with a unique personality of its own.

However, according to the University of West Indies, it’s unlikely a volcano in the Eastern Caribbean would erupt without warning. Long before a volcano erupts it would give clues such as small earthquakes, changes in gas chemistry or swelling of the mountain.

If you’re concerned about the possibility of volcanic activity while traveling to a volcanic island in the Caribbean check out the News section of the University of West Indies’ website.

Origins of Animal and Plant Life on The Caribbean Islands

Continental and tectonic islands were once part of a larger mass of land so it seems logical that animals and plants are similar to mainland life. However, many species on the island were able to flourish or avoid extinction due to less prey.

For example, today the Cuban Crocodile exists only in Cuba.

Coral and volcanic islands formed from beneath the sea so there were no pre-existing animals or plants. Plants were primarily carried to the island from birds as they dropped their seed-containing waste from the sky (you know, poop).

Some animals evolved uniquely on the islands as a result of millions of years of adaptation. 

For example one of the world’s largest frog called the “Mountain Chicken” is only found in the Caribbean Islands of Montserrat and Dominica. Sidenote: today Mountain Chickens are on the endangered species list. Hunting and volcanic activity on the islands has dramatically decreased the population

Related Questions

Which Caribbean island has the highest peak?

Duarte Peak in the Dominican Republic on Hispaniola Island rises to 10,417 feet above sea level. 

When were the Caribbean Islands discovered?

The first inhabitants of the Caribbean Islands were Amerindians (not to be confused with American Indians). However, Italian explorer Christopher Columbus was first European to visit the islands in 1492 staking claim for the Spanish monarchy in which he was commissioned.

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