Over 70% of Jamaica's land is limestone, which is composed mainly of calcium carbonate. Limestone weathers through carbonation as rainwater mixes with carbon dioxide to form a weak acid that dissolves calcium carbonate. This process forms several distinctive karst landforms, including clints and grikes (flat limestone surfaces separated by narrow grooves), sinkholes, swallow holes, poljes (flat-floored limestone basins), and resurgent streams. Cockpit country is known for its tower karst and cockpit landscapes formed by the intersection and erosion of limestone joints. Underground streams and caves form as carbonic acid dissolves limestone along joints and bedding planes. St

1. EXPLAIN THE FORMATION OF LIMESTONE FEATURES
IN THE CARIBBEAN

2. Over 70% of Jamaica’s total land surface is made up of limestone rock. Limestone is mainly
composed of the mineral calcium carbonate. The island experiences a tropical marine climate
with rain falling most of the year, and high temperatures for most of the year. This abundance of
water, heat and calcium carbonate are the exact requirements for the chemical weathering process
of carbonation. In carbonation, rain mixes with carbon dioxide gas in the atmosphere to
produce a weak acid called carbonic acid. Limestone is a porous rock, this means it allows water
to pass through it. This acid enters the structure of limestone through its cracks, pores, joints and
bedding planes where it chemically changes the insoluble calcium carbonate minerals in
limestone to soluble calcium bicarbonate.

3. Surface features are those visible above ground, they include:
Clints and Grikes
Sink holes
Swallow holes
Poljes
Resurgent streams
Cockpits
Tower Karst
Underground features are those found under the Earth’s surface. They include:
Underground stream
Caves
Drip Features
The Cockpit country which stretches through the parishes of St. Ann and Trelawny, and Lluidas Vale
in St. Catherine, Jamaica are known for their karst landscape. Lets look at how these landforms are
created and observe some examples from the sites mentioned.

4. SURFACE FEATURES
CLINTS AND GRIKES
Carbonic acid enters areas of weakness in
limestone (joints, cracks, pores, bedding
planes) wearing these areas down to form
narrow grooves in between the limestone
pavement. These narrow grooves are called
grikes. The flat limestone surfaces are called
clints. Can you identify the clints and grikes
from the picture?

5. SINK HOLE
Watch the video to see how
sinkholes are formed.
Question: How is water able to
form a hole or void in limestone?

6. SURFACE FEATURES
SWALLOW HOLE
A swallow hole like the one seen in
the photograph (at right) of the One
Eye River, Wallingford,Cockpit
country, Jamaica, marks the area
where a surface stream disappears in
the limestone to flow underground.
Swallow hole

7. POLJE
The polje such as the one seen in
the photograph at Lluidas Vale, St.
Catherine, Jamaica. The picture
shows that a polje is a long basin
with a flat floor and steep walls.
Rivers brought down alluvial soil
and deposited it inside the basin to
form the floor of the polje.
Farming is therefpre practiced on
this polje since the soil is fertile.
Polje Floor

8. RESURGENT STREAM
Rivers which flow underground through
limestone will be forced to come back
up on the surface when they meet upon
impermeable rock such as granite as
shown in the picture of the Dornock
river head in Stewart Town, Trelawny,
(Cockpit country) This is the largest
river rising in Jamaica and is the
resurgence for two rivers which flow
underground – Quashie’s river and the
Cane River. It forms the source of the
Rio Bueno river.
Resurgence Point

9. COCKPITS AND TOWER
KARST
Cockpits are small rounded hills interspersed
with depression (Ottley, Gentles, 2006). They
are formed wherever limestone joints from a criss
cross or star shaped pattern Carbonic acid then
enters the limestone where the joints intersect.
These areas are eroded to form solution basins.
The unweathered portion of the limestone will
stand out as a cockpit hill. Go to
www.cockpitcountry.com/landscapeimgs/film.cc.
swf to watch a movie on cockpit formation.
Overtime, continuous chemical weathering on
limestone will wear away the sides so that they
look almost vertical. At this stage, the cockpit is
called a tower karst. Example, in Warsop,
Trelawny (Cockpit country) as shown in
photograph.
Tower Karst

10. UNDERGROUND FEATURES
UNDERGROUND STREAM
Observe the map of the One Eye River on the next page. Observe where it breaks at Wallingford,
indicated by the brown arrow. That area shows where it sinks underground in the limestone rock
(also shown in the picture) to become an underground stream. It also shows the extent of its
underground journey (Source of map: UK D0OS map sheet 19959).

12. CAVES AND DRIP
FEATURES
According to Rahil (1994) calcium
carbonate in underground water
flowing along the bedding planes and
joints of limestone rock will dissolve
the rock to form large underground
passages called caves. When the roof
of a cave collapses, a gorge is formed.
Carbonated water passing through
cracks and pores in the roof of a cave
will form drip features as shown in the
photograph taken in the Swansea
Caves, Lluidas Vale, St. Catherine,
Jamaica.
Stalactite
Stalagmite

13. Carbonated water passing through cracks in the roof of a cave will dissolve the calcium carbonate
in the roof. Water droplets mixed with calcite will settle on the roof . Each droplet which hangs
from the ceiling will lose water and carbon dioxide by evaporation causing a thin layer of calcite to
be left behind. “Successive drops add a layer after layer building up the calcite (Rahil, 1999).
These deposits on the roof will build up into a long column of calcium bicarbonate which hangs
downwards called stalactites (see picture in Swansea cave).
Some of the water mixed with calcite will drip slowly from the roof to the floor. As the
water and carbon dioxide exaporates, these will build up and grow upwards forming stalagmites as
shown in the photograph in Swansea caves. Overtime, a stalactite and stalagmite will join together
since they are directly aligned from top to bottom. This will form a pillar. The picture of the drip
features show that the stalactite and stalagmite may become a pillar in the near future.

14. REFERENCES
Ottley, Gentles “Longman Geography for CSEC, Hodder Education, 2015
Rahil V. “New Caribbean Geography with Map Reading and CXC Questions,
Eniath’s Printing Company Ltd, 1994
The One Eye River, UK D0OS map, sheet 1959