Geography Answer Writing Practice 2018 - Week 5 - Question 3
90 Days Geography Answer Writing Practice Question 1 for 12-Dec-2018
Instructions for Writing Answer
1. Write your answers in the comment section.
2. Experts will provide their feedback in reply.
3. Model Answers will be uploaded on this page the next day.
4. Rectify your mistakes and progress further.
5. All the Best.
12-Dec-2018 - Question 1
Illustrate the origin and nature of Sargasso Sea and Lagoon. 150 words (2014)
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The Sargasso sea is a motionless sea confined to the sub-tropical north atlantic gyre. Its origin can be attributed to several factors:
- The gyral system formed by the anti-cyclonic circulation of the North Equatorial current, the Gulf Stream and the Canary current confining the water from the rest of the ocean.
- Atmospheric stability due to it being located in the transition zone of the trade winds and the westerlies which is characterised by anti-cyclonic conditions. Hence there are feeble winds which allow little intermixing with waters outside the gyre.
- The less extensive nature of the North Atlantic Ocean between 20°N-40°N than other oceans in the same latitudes.
- The higher velocity of the North Equatorial Current and the Gulf Stream create calm waters in the confined region.
Nature of Sargasso Sea:
- Highest salinity 37 %o due to high temperature and evaporation, also increases due to no intermixing of water.
- Mean annual temperature is 28 degree C.
- Sea is covered with rootless sea weeds which obstructs navigations.
- It is a spawning site for threatened and endangered Eels, as well as white Marlin, porbeagle Shark, and Dolphinfish.
- Sargassum seaweed, is a unique free floating organism found here.
A lagoon is a shallow enclosed body of water that is separated from the ocean by sandbars, barrier islands, or coral reefs. Their origin can be due to either of the mechanisms:
- Deposition by sea waves of debris leading to the build of sand bars and barriers on shallow platforms near the shore. This creates an obstruction which can then grow around the island and form a complete enclosure with a few breaks.
Formation of lagoon due to sandbars
2. Darwin’s theory of subsidence states that the coral reef grows upward and outward during the subsidence of an island leading to the formation of barrier reefs which form a lagoon.
Formation of lagoon due to Barrier reef and subsidence. The levels A1, A2 and A3 represent rising sea levels as the mountain/island subsides.
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