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 result from 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 is another example of a continental island.

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 volcano erupts and 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 the 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, and 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 the 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 and 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.

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 Islands 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.

Ever wondered why the Caribbean Sea is so blue? I did, too! I dove into the science and wrote Why The Caribbean Water is so Blue. << a must-read!

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 by birds as they dropped their seed-containing waste from the sky (you know, poop).

Some animals evolved uniquely on the islands due to millions of years of adaptation. 

For example, one of the world’s largest frogs, 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 have dramatically decreased the population.

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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 the first European to visit the islands in 1492, staking claim to the Spanish monarchy in which he was commissioned.