Questions on natural systems
Marjorie Henry, Contributor

I will certainly keep my promise today to answer Question 3 from the June 2008 examination. I hope you held on to the lesson with the question. This is another question from Section B of the question paper, the section that deals with natural systems. The question is testing the following specific objectives as indicated in your syllabus:

• Describe how water flows on reaching Earth's surface.
• Describe river and wave processes.
• Describe the types and location of coral reefs found within the Caribbean and the conditions necessary for successful coral reef formation.

As I have already indicated, in this question you are not given a stimulus material in part (a), but rather you are requested to produce it by drawing a diagram of a meander. This is, of course, referring to a feature formed in the lower course of the river. May I suggest that you refer to your textbooks and identify a diagram showing a meander and practise to draw it. Notice that you are asked to label THREE main features of the meander. These are as follows:

• Area of rapid erosion
• Area of deposition or point bar
• River cliff
• Slip-off slope
• Where the fastest flow occurs.

Remember to do your drawing with a pencil. This should be neat and clear. PRINT when labelling, using a pen.

Part (b) (i) asks you to state FOUR conditions that are required for the successful growth of coral reefs. Here is a list taken from Geography for CSEC by Jeanette Ottley, et al, one of the recommended textbooks for this course:

1. Warm seawater between 25º and 27ºC: cold water slows the growth, but if the water is too warm it bleaches the corals, eventually killing them.

2. Sunlight is necessary for photosynthesis; it allows the microscopic plants that corals feed on to make their food. These microscopic plants live in the tissue of coral polyps where they get nutrients and protection. In exchange, the corals have a ready supply of food.

3. The water must be clean, clear and well-oxygenated: clear water enables sunlight to penetrate easily. Water that is polluted or carries a lot of sediment is not suitable. The sediment makes the water cloudy, preventing sunlight from penetrating the seawater. Sediments also choke the corals.

4. Corals grow best as a depth of 20-40m; this allows for the penetration of sunlight (light penetration becomes difficult below 100m). The depth of water also affects temperature, as temperature decreases with depth of water.

5. Normal seawater salinity, together with gentle wave movement: corals will not grow where the water is not salty enough, for example, at the mouth of a river, or where it is too salty.

You can add diagrams when answering part (b) (ii). Here you are asked for a description of fringing reefs and barrier reefs. The following information is from General Geography in Diagrams written by R. B. Bunnett. Practise to draw the diagrams of the reefs as found in this text.

Fringing reef

This type of reef consists of a platform of coral which is connected to and which is built out from a coast. The surface of the platform is usually flat or slightly concave and its outer edge drops away steeply to the surrounding sea floor. A shallow lagoon usually occurs between the coast and the outer edge of the reef.

Barrier reef

This reef is similar to a fringing reef except that it is situated several miles off the coast and is separated from it by a deep-water lagoon.

I will discuss the remainder of the question in the next lesson.

Charlemount High School duo, Verlando Small and Reneive Fletcher, performs Lionel Richie and Diana Ross smash hit 'Endless Love' during the JCDC/St Catherine Cooperative Credit Union-sponsored St Catherine Festival Queen grand coronation show held at Portmore HEART Academy, on Sunday, May 17. - Anthony Minott/Freelance Photographer