Seychelles: More than just a pretty face


During CBC`s recent travels, the Media and French club set sail for the beautiful coast of the Seychelles. Beautiful, why? You might ask. The coast is a unique and dynamic environment: exotic plant and animal life inhabits these coasts and we can see coastal erosion processes at their best. For a geography student like me, studying the coast is more exciting than watching the world cup.
One feature that became prominent from the trip was the presence of coral reefs. The genesis of these unique Coral reefs came from underwater structures made from calcium carbonate secreted by corals. Coral reefs are formed from colonies of tiny animals found in marine waters that contain few nutrients. Most coral reefs are built from stony corals, which in turn consist of polyps that cluster in groups. The polyps belong to a group of animals known as Cnidaria, which also includes sea anemones and jellyfish. Unlike sea anemones, coral polyps secrete hard carbonate exoskeletons which support and protect their bodies. Reefs grow best in warm, shallow, clear, sunny and agitated waters.
Just as coral reefs were found, several coastal erosion processes also came to light. Firstly wave pounding, the name says it all, waves produce 30 tonnes of pressure and this is directed at the base of the cliff; with this continued pounding the compatibility of the cliffs results in pieces falling off. Secondly, hydraulic pressure and, in case you are wondering, it doesn’t involve a car. Surges of waves trap air in the cracks of the rocks and compress them; when the water retreats the air expands making the cracks enlarge. Thirdly is abrasion. The waves transport rock and sand particles that scratch and hit the cliff; this weakens the cliff and, again, pieces fall off. Fourth is attrition. Rock particles within the wave collide into each other causing the rocks to fragment and divide into small pieces; they are transported on to the beach and create its profile, which I will touch on later. Solution: the sea is home to some weak acids which react chemically with the rocks which are soluble in water, for example carbonic acid in sea water. Plus calcium carbonate of limestone rocks create calcium bicarbonate which is soluble in water. Finally the last erosion process which doesn’t involve marine action at all is sub-aerial erosion; this is the impact of rainwater, wind and frost. Rainwater can erode the surface of the cliff giving it wonderful and abstract shapes as found in the Seychelles.
One last mention of the beautiful coastline of Seychelles, which has a unique beach profile due to the influence of high and low energy waves: the clear, golden crisp sand is a sign that low energy waves are present as they bring sand particles for deposition on the beach, which gives it a flat, wide gradient. However very minor parts of the beach are under the influence of high energy waves, which percolate through the large air space within the pile of rocks at the backshore as high energy waves can carry heavier rock particles further on to the beach giving it a narrow, steep gradient.
As a geography department we would like to commend the Media Club boys for their participation in this trip and for giving us photos of the sumptuous sands and omnipresent oceans of the Seychelles. We hope that after this success the college can co-ordinate more beneficial trips such as this one.
Gamuchirayi Manungo 
U6 Geography Student


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