Structure of sa

Geography

Grade 5

The physical structure of south africa

Module 7

The structure of the rsa

• The surface of the RSA is not as flat as a tabletop. The uneven nature of the surface has to do with the structure or morphology of the land. Landforms such as coastal plains, lowlands, plateaux, mountains and rivers constitute the structure of the land.
• If you look at the relief map of the RSA below, or at any physical map of the RSA in an atlas, you will understand that different parts of our country are situated on different altitudes above sea level.

Figure 1

• Different colours are used on such a relief map to indicate the different altitudes above sea level:

Green = lowest areas, e.g. coastal regions

Yellow = just higher than the green areas (Little Karoo)

Orange = higher areas

Brown = mountains

Purple / white = highest mountain peaks

Blue = water

• Use your atlas and colour your map according to the above-mentioned colour key.

Morphological areas of the rsa

Coastline and coastal plains

• The coastline is the area where the land meets the sea. The RSA has a very long and almost unbroken coastline with few capes (points such as Cape Point) and few bays (such as Table Bay and False Bay). The only area where both these are to be found, is the Cape Peninsula.

Figure 2

• The coastal plain is the low-lying area along the coast. The coastal plain of the RSA forms a narrow band between the sea and the mountains of the escarpment.

The little karoo and the great karoo

Figure 3

• There is, however, an area between the sea and the escarpment where one first has to climb a few “steps” to reach the escarpment. These “steps” are called the Karoo. “Karoo” is a word meaning hard. Thus it is a hard, dry region.
• It comprises two flat smaller plateaux between mountain ranges.
• From the south coast (Mossel Bay) the land rises gradually from the coastal plain to the Outeniqua Mountains and the Langeberg. The low-lying area that follows this and lies just before the Swartberg Mountains is called the Little Karoo. To the north of the Swartberg range lies the Great Karoo , which is situated one step higher than the Little Karoo. It is found just before the Nuweveld Mountains, which form part of the escarpment.

Plateau and escarpment

• The escarpment indicates where the plateau of the interior begins, and forms an unbroken mountain chain. It begins with the Kamiesberg range in the northwest, and towards the south it becomes the Roggeveld Mountains . It then veers towards the east, where the Nuweveld , Sneeu , and Storm mountain ranges are found. In the northwest one finds the Drakensberg range. Here the escarpment is much higher than elsewhere. The highest peaks of the Drakensberg are Mont-Aux-Sources (3 299 m) and Thaba Ntlenyana (3 482 m). The escarpment forms our country’s most important watershed.
• The mountains of South Africa were formed by curvature, shifting or folding, just like all other mountains throughout the world. The Hex River Mountains, the Cederberg Mountains, the Swartberg range and the Langeberg Mountains are, for example, all fold mountains in sedimentary rock. Many of these have become flattened by erosion, and one does not see much of it. Examples of igneous rock can be seen in the Drakensberg range.
• Unfortunately the escarpment prevents moist air from the sea reaching the interior plateau , which causes frequent droughts in the interior of the country.
• The interior plateau is the vast stretch of land that is situated to the interior of the escarpment. It covers the greatest part of the RSA and lies from 900 m (west) to 3 000 m (east) above sea level.