Limestone is a sedimentary rock primarily made of calcium carbonate, formed from organic matter in warm marine environments. It has various types, such as carboniferous, jurassic, oolitic, and chalk, and undergoes processes like carbonation and frost action, leading to unique geological formations like caves and karst landscapes. The document discusses the characteristics, formation, and features of limestone, including various geological processes that shape its structure.

2. What is limestone?
Limestone is a Sedimentary Rock composed primarily of
Calcium Carbonate [CaCO3
] in the form of the mineral
Calcite. It is an organic sedimentary rock that forms from that
accumulation of shell, coral, algae and fecal matter in clear,
warm, shallow marine waters.
Characteristics:
● Limestone areas are littered
with cracks and joints;
● Limestone rock is
permeable and porous;
● Limestone can be easily
weathered.
● Limestone can undergo
metamorphism resulting in it
recrystallizing as marble.

3. Types of Limestone:
● Carboniferous Limestone - this
grey limestone forms upland
areas in the UK, such as Pennine
Hills, it was formed some 340
million years ago in tropical seas
that were rich in shellfish and
corals.
● Jurassic Limestone - this type of
limestone is found throughout the
Caribbean. Formed 120-150
million years ago it is widespread
in Cuba, Jamaica and Puerto
Rico.

4. ● Oolitic Limestone - are tiny balls of
limestone, usually smaller than a
pea. When a small fragment of
shell or rock is rolled on the
seabed, calcium carbonate
dissolved in the water may be
precipitated to form limestone.
Over time, as more and more
limestone forms on the shell or rock
fragment, it grows in size to form
an oolith. The oolith eventually
form great thickness and become
compresses to form Oolitic
Limestone. In the Caribbean,
Oolitic Limestone can be found on
the Turks and Caicos Islands. It is
currently being formed on the
Bahamas Platform.

5. ● Chalk - is a white type of
limestone that was formed
in the Cretaceous
geological period [145-65
million years ago]. It is very
rich in calcium carbonate
[97%] and is commonly
found in the UK.

6. Processes:
● Carbonation - this type of
chemical weathering is very
effective because limestone is so
rich in calcium carbonate.
Rainwater that has absorbed
carbon dioxide from the air
becomes mildly acidic [carbonic
acid]. This reacts with the calcium
carbonate and causes it to slowly
dissolve. Carbon dioxide is more
soluble in colder conditions. This
explains why carbonation in the
Caribbean is more likely to be
effective during cooler nights
rather than during the day.
Chemical weathering
is responsible for
producing the
extraordinary jagged
limestone outcrop at
Hell on Grand
Cayman.
The formula for carbonation
is:
CaCO3
+ CO2
+ H2
O =

7. ● Frost Action - this is common in temperate regions of the
world. Water can collect in joints and cracks in the
limestone. When it freezes, it expands, forcing the crack
apart. Repeated cycles of freezing and thawing will
eventually cause fragments of rock to break away.
● Mass wasting - occasionally blocks of limestone may
become detached resulting in landslides. Frost action
may be responsible for rockfalls, when individual rock
fragments fall from cliffs.
● River erosion - limestone is pervious and water will readily
flow through the joints and along bedding planes,
sometimes forming fast-flowing underground rivers.
These rivers are capable of carrying out intensive erosion
to form features such as caverns. On the surface,
however, there will be few rivers. This lack of surface river
erosion partly explains why limestone tends to form
upland areas.

8. The Uses of Limestone:

9. Limestone Features:

10. Surface Limestone Features: When rainwater falls on to
exposed limestone or rivers flow
into an area of limestone, it
passes through joints in the
rock. Carbonation leads to the
weathering of the surface of
the limestone and the joints
within the rock. As a result, the
joints become wider. The
widening of the joints leads to
the creation of grooves or gaps
in the limestone called grikes.
The blocks that are left in
between these grikes are
called clints. The carbonation
of these features leads to the
creation of a limestone
pavement.

12. Rivers flowing into a
limestones area moves
through spaces and
vertical joints [grikes]
slowly dissolving
limestone through the
process of solution. As the
limestone dissolves, pores
and cracks are enlarges
forming swallow or
sinkholes.

13. Sink/Swallow
Hole

14. Underground Limestone Features:
When a stream disappears in a limestone area it travels underground
through a complex series caves and eventually works its way down to a
level of impermeable rock till it reaches the surface as a resurgent stream.
Caves often form in limestone areas when underground water containing
carbon dioxide. The slowly moving groundwater dissolves the rocks along
joints and bedding planes to form tunnels and irregular passages or
caves.
Water dripping from the ceiling of a cave contains dissolved Calcium
Carbonate. Some of this Calcium Carbonate may be deposited on the
ceiling of the cave. Overtime the deposition of Calcium Carbonate will
form elongated features which hangs down from the ceiling. This feature
is known as a stalactite.
As water drips from the ceiling onto the floor of the cave, Calcium
Carbonate may be deposited on the floor of the cave. Overtime this may
form an elongated feature which rises vertically from the cave floor. This
feature is known as a stalagmite.

15. Water dripping from the ceiling of a cave contains dissolved Calcium
Carbonate. Some of this Calcium Carbonate may be deposited on the
ceiling of the cave. Overtime the deposition of Calcium Carbonate will
form elongated feature which hangs down from the ceiling. This feature is
known as a stalactite.
As water drips from the ceiling onto the floor of the cave, Calcium
Carbonate may be deposited on the floor of the cave. Overtime this may
form an elongated feature which rises vertically from the cave floor. This
feature is known as a stalagmite.
The stalactite may continue to grow downwards and the stalagmite may
continue to grow upwards until the two limestone features eventually
meet. When this happens they form a new feature known as a
pillar/column which extends all the way from the ceiling of the cave to
the floor.
Stream

16. Stream

18. Karst Topography
Karst topography refers to natural features produced on a land
surface due to the chemical weathering or slow dissolving of
limestone.. The chemical weathering agent is slightly acidic
groundwater that begins as rainwater. Rainwater becomes acidic
by absorbing carbon dioxide to create carbonic acid as it falls
through the atmosphere. It then passes through the soil horizon
and, now acidic groundwater, moves through fractures [cracks]
and open spaces within rocks. Solution occurs as carbonic acid in
groundwater dissolves calcite, which is the principal mineral in
limestone.
Features of karst landscapes include caves, springs, disappearing
streams, dry valleys, and sinkholes. Acidic groundwater moves
through fractures and spaces within the rock, slowly dissolving and
enlarging spaces to create larger openings and connected
passages.

19. Caves occur as natural open spaces underground, generally with
a connection to the surface and large enough for a person to
enter. Underground passages allow groundwater to travel long
distances and re-appear as springs.
Springs occur where groundwater flows naturally from a bedrock
or soil onto the land surface or into a body of surface water. On
the surface, a stream can disappear into the subsurface through
fractures and passageways and travel underground for some
distance before reappearing downstream as a spring elsewhere.
These streams are called disappearing streams. In areas where
the stream is mostly dry year round, the valley is called a dry
valley.
Dry valleys are valleys devoid or almost devoid of running water
and are common in areas underlain by carbonate rock with
underground drainage.
Sinkholes commonly occur as bowl- or funnel-shaped circular
depressions and usually are the surface expression of
underground drainage. Sinkholes form by solution, solution
subsidence, and collapse.

20. Solution sinkholes form as water infiltrates fractures in rock,
dissolving and enlarging them. A gradual settling or lowering of
the surface takes place, forming a depression. When carbonate
rock is overlain by an insoluble rock such as sandstone, the
underlying carbonate rock can undergo solution producing a
void. This causes the overlying sandstone to subside into the void,
producing solution subsidence sinkholes. Collapse sinkholes form
when strata overlying a cave chamber collapse into the
chamber.

23. Karst is a type of landscape where the dissolving of the bedrock
has created sinkholes, sinking streams, caves, springs, and other
characteristic features. Karst is associated with soluble rock types
such as limestone, marble, and gypsum. In general, a typical karst
landscape forms when much of the water falling on the surface
interacts with and enters the subsurface through cracks, fractures,
and holes that have been dissolved into the bedrock. After
traveling underground, sometimes for long distances, this water is
then discharged from springs, many of which are cave entrances.
● Cockpit country is made of limestone. Limestone is formed
under the sea by the accumulated skeletons of sea-dwelling
creatures such as molluscs and coral.
● The formation of Cockpit Country started about 15 million
years ago when Jamaica emerged from the sea. The faulted
limestone plateau rose to about 600m (2,000ft) above sea
level. Erosion of this plateau formed the regular array of
round-topped, conical hills and sinks that is the type location
for cockpit karst.

24. ● The "solution" theory proposes that heavy tropical rainfall
washing through a fissured limestone plateau over millions of
years dissolved and eroded the fissures and washed the debris
through the sinkholes eventually out to sea.
● The "collapse" theory maintains that the formation and
subsequent collapse of cave systems is the primary
mechanism for cockpit karst formation.
Caves develop, join together, grow -
and eventually collapse, leaving
behind the ‘walls’ and columns
between the caves, which are
simply the same limestone as the
caves developed in, just the parts
that didn’t dissolve as quickly.
Eventually, those ‘towers’ will also
collapse, dissolve,leaving behind a
simple plain.

25. MCQ:
Limestone is composed mainly of a mineral called
calcium carbonate.
● True
● False
Limestone is NOT usually formed under water.
● True
● False
Limestone is an impermeable rock.
● True
● False

26. Limestone can be slowly dissolved by rainwater or
groundwater.
● True
● False
This feature is formed when calcium carbonate is
deposited on the ceiling of a cave.
● stalagmite
● sinkhole
● stalactite
● pillar

27. This feature is formed when the roof of an
underground cavern collapses.
● stalagmite
● sinkhole
● stalactite
● pillar
This feature is formed when calcium carbonate is
deposited on the floor of a cave.
● stalagmite
● sinkhole
● stalactite
● pillar

28. When a stalactite and a stalagmite meet they form a
new feature known as a:
● cave
● stalactite
● cockpit
● pillar
Sometimes a large underground hollow or passage
called a _________ is formed as water wears away
limestone.
● underground river
● cave
● cockpit
● karst landscape

29. The name given to the distinctive landscapes which
form in limestone areas is:
● cockpits
● sinkholes
● cave systems
● karst
A large area with many small hills and depressions
which forms in limestone is known as:
● cockpits
● sinkholes
● cave systems
● karst

30. THE