Geological Features - North Clarendon

Question: What physical formation exists in your community- rivers, valleys, mountains plains, etc use photograph where possible?

 

by:  Henry Jones Givans

The forces which cause physical features

 1 Internal

(a) Vertical- (Up and down) movements produce faulting crustal rocks.

(b) Lateral- (sideways) movements called folding of crustal rocks

2 External

(a) Weathering- this is the deterioration of rocks by either heating or cooling; chemical actions and actions of living organisms.

(b) Erosion- the deterioration of rock particles by the movement of water, wind and ice.

© Transport - This is the movement of rock particles over the earth’s surface by water wind and ice.

The physical formations of the Chapelton Community are:

1.   Mountains

2.   Rivers

3.   Valleys

4.   Springs

5.   Hills

6.   Cliffs

7.   Gullies

Mountains

These are land form features with heights of at least 2000 feet or 600m above sea level. In Jamaica a high land over 300m is called a mountain.

There are three ways in which mountains can be formed:

1.    Folding

2.    Faulting

3.    Vulcanicity

Folding

This is the process by which sedimentary rock strata bend into anticlines or synclines as a result of compression (forces acting as shown) below in the earth’s crust→ ←.

Types of Folding

1.    Simple or Symmetrical

2.    Asymmetrical

3.    Over fold or Recumbent

4.    Over thrust or Nappe

Simple or Symmetrical

The simplest form of folding is symmetrical, this occurs when the rock strata are bent into an anticline and corresponding syncline.

Asymmetrical

This occurs when compression acting on a simple fold forces one side of the limb to be steeper than the other.

Over fold or Recumbent

This occurs when one limb is pushed over the other.

Over thrust or Nappe

in cases of extreme pressure a fracture occurs and one limb is pushed over the other.

Features produced by folding

Fold Mountains: the folding and uplifting of the crust as a result of compression forces acting in opposite directions as shown  

form these.

Faulting

This is the process by which sedimentary rock strata break rather than fold. Faulting is caused by both compression and tension. A fault is a crack or fracture in the earths crust.

Types of Faulting

1.    Normal Fault (tension)

2.    Reverse Fault  (compression)

3.    Transform Fault / Tear Fault (compression)

Normal Fault

This occurs when tension pulls on sedimentary rocks, if the rock breaks along a steep incline plane one side will slip vertically to the other.

Reverse Fault

This occurs when sedimentary rocks are pushed together as a result of compression, if the rock breaks along a steep incline fault plane one side will be forced to override the other.

Transform Fault/ Tear fault

This occurs when rocks are being forced pass each other without any vertical displacement. When this takes place the earths crust is torn.

Features produced by Faulting

1.   Block Mountain (Horst)

2.   Rift Valley (Graben)

3.   Fault Scarp (Cliff)

Block Mountain

This occurs when an individual block or fault is left upstanding either by the sinking of the crust on both sides of a pair of faults, formed by compression.

Rift Valley

Is an instance where an instance of the earths crust is lowered between faults. Rift valleys are the reverse of a horst. They are formed by compression and tension.

Fault Scarp

Faulting influences land scape by giving rise to cliffs called scarps, scarps can be found on the side of a block mountain.

    As a result of the above movements in the earths crust, mountains and hills are present in and around the community.

The main mountains in and around the Chapelton community are

1.    Mocho Mountain - This is over 1500 m high this serves as a natural habitat for animals such as birds, snakes etc and many other species of animals, and trees. It also serves as a feeding area for animals such as goat’s pigs, cows etc.

2.    Bull Head Mountain - this is about 1800 m high. This mountain serves as main water shed for the Rio Minho river. This mountain also attracts tourists because each year a camp is kept at the peak of the mountain.   Every year at Ash Wednesday, Bull Head Mountain attract many persons who go there for the view, the music, the food, socializing and just to relax.  (Stay tuned for more on Bull Head Mountain as an attraction).

Hills

These are high lands generally under 2000 feet or 600m.

 There are many hills in the Chapelton community. Firstly Clarendon College is built on a hill, other hills in the community are:

1.    Salem hill

2.    Crofts hill

3.    Green hill

4.    Goring hill

5.    Trafalgar hill

  These hills mentioned are the main hills present in the community. 

Valleys

A valley is an area of low land between high lands.

There are many valleys in the Chapelton community although there are no specific names. They are also cliffs present.

Rivers

River- A river is a body of fresh water, which flows through a natural channel from its source t a sea or lake.

There are 3 main rivers running through the Chapelton community these are:

1.    Rio Minho - This is the longest river in the island of Jamaica. It serves as a natural habitat for fishes, shrimps, crabs, crocodiles and many other microorganisms. It is also a water source for plants and animals.

2.    Thomas river- This river feeds the Rio Minho

3.    There is also the Pindars river which also feds the Rio Minho.

The rivers in the community produce eloda, which feeds the manatees.  They also grow mangrove and serve as a natural habitat for aquatic life.  The river also serves as an ecosystem.

There are many springs in the community, which rises above the surface of the earth and acts as a water supply foe the members of the community.

Rocks

These are the solid parts of the earths crust.  They are made up of minerals; they differ in colour, texture and structure. Rocks can be classified according to their method of formation.

There are three types of rocks

These rocks are representatives of lime stones that lie adjacent to our first and second form block at Clarendon College

1.    Igneous

2.    Sedimentary

3.    Metamorphic

There are only two types of rock formation in the community these are Sedimentary and Metamorphic and are discussed below.

Sedimentary

  These are rocks composed of particles of pre-existing rocks such as igneous and metamorphic and the remains of plants and animals that have been cemented together.

Sedimentary rocks are formed in layers that have been deposited by wind and water.  The plane of division between each stratum is called the bedding plane.  This indicates where one phase of deposition ends and the other begins. Sedimentary rocks are

1.    Sandstone

2.    Lime stone

3.    Chalk

4.    Coal

5.    Clay

6.    Gravel

Metamorphic

These are rocks in which pre-existing rocks both Igneous and Sedimentary have undergone a physical or chemical change by heat and pressure causing the structure to change.  Any rock could be changed into a metamorphic rock. Metamorphic rocks are

1.    Marble from lime stone

2.   Slate from clay

3.   Gneiss from granite

4.   Quartzite from sand

5.   Graphite from coal