Most of the rock found on The Bahamas are limestone, the limestone formed as coral reefs and were shaped by the wind, which may include embedded shells
Unlike most islands there is very little volcanic rock on The Bahamas.
You can expect to find various types of limestone, but not much else.
There are many types of limestone in The Bahamas that may be interesting to observe.
Types of Rocks Found in The Bahamas
The information provided in this article by YesDirt.com is for informational purposes and is subject to change. Laws are updated. Accessibility guidelines and restrictions change. Be sure to confirm the land status and collection rules before you travel to an unfamiliar location or collect any material.
The white sands of The Bahamas archipelago are chalk limestone.
This type of rock can be found all over any of the 700 islands that make up The Bahamas.
Chalk limestone is very light in color and very hard.
It may also be identified by the presence of fossils.
It is a type of Biological Limestone.
These are sedimentary rocks formed by the compression of shells of marine life.
In shallow warm water animals may form calcium carbonate shells.
Animals native to The Bahamas; corals, conch, sand snails, and scallops form these shells and when they die the shells can compress into chalk limestone.
This is known as Biological Limestone because it is formed with the aid of the animals that create the shells.
Chalk limestone may contain fossils of shells that did not completely break down in the rock formation process.
Chalk limestone will react by foaming with carbon dioxide bubbled when exposed to a dilute acid solution.
This is called an acid test and may be performed by geologists studying the rock.
You may find Oolites if you find yourself on The Great Bahama Bank you may spot some Oolites.
Ooids are small round stones that are formed in concentric circles.
Some particles form the center and other material is deposited to form a perfect coating in warm water that constantly rotates the forming ooid.
The Bahaman ooids are grains of sand coated in layers of calcium carbonate.
They look like large, round grains of sand and they are cemented together into oolites.
These rocks have been extensively researched on the island and if you visit this location you will see many examples and learn more about these formations.
No one is sure how Ooids came to be on The Great Bahama Bank as the conditions for their productions are not present in current conditions.
Geologists hope that studying these special formations can help them understand more about how the islands were formed, historical ocean currents and temperatures.
Fossiliferous Limestone is limestone that contains many preserved shells or fossils.
Fossiliferous limestone can range from white to black and it may initially look sponge-like. A rock with many visible holes and dimples.
Fossiliferous limestone is formed when shells are trapped in a calcium-containing mud, and becomes compressed into rock.
Fossiliferous limestone is a sedimentary rock even though it may appear to be a conglomerate.
You will notice two distinct aspects of the fossiliferous limestone, the ‘mud’ or solid limestone and the fossils which may be smoother or darker in color.
These exciting finds can show the type of life that was present when the rock was formed.
You may be able to make out the shapes of small shell fossils or they may be microscopic fossils like those of diatoms or other single or two celled organisms that may contribute to the formation of biological limestone.
Fossiliferous limestone can be classified by where it was formed and is generally one of the following types:
- Shallow Water
- Deep Sea
They may also be classified as evaporative, but this is not present in The Bahamas.
Conquita limestone looks like a collection of cobbled together shells and other fossils.
These shells are cemented together in a limestone mud, and they can be a variety of colors.
They are easy to identify as they are made up of shell or shell fragments that are visible.
There are a few types of Coquina limestone:
These smaller coquinas are often formed in Sea Lilies and they are made up of finer shells and fossils.
They are still discernible shells, but the texture may appear more regular.
Some of the shells may be microscopic and not immediately visible.
Coquinite is a harder formation of a Coquina.
They may be visible above water and they will have a smoother look. It may look more like regular limestone.
Limestone Formation on The Bahamas
Most of the rocks on The Bahamas are limestone, but the formations of limestone can make the limestone take on various appearances.
Subareal limestone are formations of limestone that have been exposed to air after forming under water.
Some limestone has reached the surface as a result of karstification, or the movement of tectonic plates supporting the limestone.
These formations have been shaped by the wind and have a rounded appearance not common with limestone.
You may notice a tumbled look of the gray limestone formations, as opposed to the large flat pieces you may have seen in creek beds.
Collecting Rocks in The Bahamas
As a general rule, do not take any samples or remove any natural material from The Bahamas without first asking a tour guide, employee or other official.
The goal is to respect the preservation of these formations so they can continue to be enjoyed and studied.
Since The Bahamas are studied by many scientists and hobbyists there may be additional guidance available on site when you are visiting The Bahamas.
Please obey all posted rules and regulations.
Types of Rocks on the Bahamas
The Bahamas are a fairly young geological formation and that means mostly limestone.
The limestone on The Bahamas is still very interesting as it gives us a glimpse back in time, and an understanding of the connection of the systems that formed this rock.
Some geologists now believe that the sand pillars that support The Bahamas may have once been a part of the Sahara Desert.
The fossil rich limestone and the confusing presence of Ooids make The Bahamas a popular place for scientific research.
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