The document outlines the key characteristics and development processes of canyon and basaltic plateau landscapes formed by horizontally layered rocks. It discusses the differences in hilly landscapes in humid versus arid areas, emphasizing the impact of weathering processes on terrain formation. Additionally, the document evaluates human utilization of these landscapes, addressing agricultural potentials and limitations for each landscape type.

1. Gr11 Geography
Geomorphology
By Mr. M DUMAKUDE

2. TERM 2- WEEK 1
Topography associated with horizontally layered rocks:
LESSON OBJECTIVES
At the end of this lesson, you should be able to do the following:
-Identify the key characteristics of canyon and basaltic plateaus formed by horizontally layered rocks
-Describe processes that are involved in the development of hilly, karoo landscapes, canyon and basaltic plateaus
-Interpret images on slides showing different landscapes
-Draw a diagram showing a scarp retreat or back-wasting
-Evaluate the impact of human utilization of landscapes, basaltic plateaus and canyons considering both positive and
negative effects on the environment and local communities
-Propose a strategy on how can we preserve basaltic plateaus for agricultural purposes

3. An image of a certain type of rock
Take a guess ???

4. Characteristics and processes associated with the development of
Hilly landscapes
WET AND HUMID AREAS CHARACTERISTICS:
 Slopes are rounded
 Undulating landscapes (Moving In waves)
 Deep soils on the slope
 Rocks are horizontally and sedimentary and uniformly resistant to erosion
 Steep hilly landscapes
 These regions typically have high rainfall with the water eroding and smoothing these hills
PROCESSES: Chemical weathering is most active

5. Valley of a Thousand Hills-KZN
 Steep and deep
 Formed by down-cutting of Umngeni River

6. Characteristics and processes associated with the development of
hilly landscapes
ARID AREAS CHARACTERISTICS:
 Landscapes are more rugged and angular
 Weathering and erosion of horizontal layers of rocks leads to steep and uneven slopes
ARID AREAS PROCESSES:
 Mechanical weathering is active due to lack of water
 There is no chemical change in the rocks. Rocks are physically broken down into smaller fragments
 Mechanical Weathering includes: Ice wedging, exfoliation, and sandblasting

7. Topography associated with horizontally layered rocks
 Horizontally layered rocks refer to sedimentary rocks as they are layered
 They form from deposits of sediments that are built up in a series of layers on the sea floor
 These parallel layers of sedimentary rocks are called beds or strata
 The junction where the layers join between sedimentary rocks are called bedding planes

8. Layers of horizontal layered rocks can be formed from:
 Lava flows
 Exposed sills (Igneous rock)
 When horizontal sedimentary rocks are uplifted without changing their horizontal position
 NB: When this type of rock is eroded, it forms canyons and basaltic plateaus

9. Canyon Landscape
 For canyons to form, the original layers of rock are level
 The harder layers of rock resist erosion and the softer layers or faults are more susceptible to erosion
 The down-cutting action by rivers, maintains the narrow, vertical profile, thus creating a canyon or gorge
 The freezing and expansion of water trapped in the cracks and faults of the rock strata, results in physical
weathering
 This process is also responsible for the formation of Canyons
 Example of the canyon: Blyde River Canyon situated in Mpumalanga province.
It is also the third-largest canyon on Earth and is situated below the confluence of Blyde and
Treur rivers

10. BASALTIC PLATEAUS
Example: Drakensburg Mountain located in South Africa, Kwa-Zulu Natal
 Basaltic plateaus are large high-lying regions formed initially from lava
flows covering thousands of square kilometres.
 This rock is eroded predominantly by water forming high, flat landforms
and deep canyons.
 Other landforms formed by erosional processes are mesas, buttes, and
domes

11. Karoo Landscapes

12. Karoo landscapes characteristics and processes
Characteristics are:
 They form due to erosion over time
 They are flat-topped hills separated by wide flat plains
 Dolerite sills form the flat tops of the hill-more resistant to erosion
Processes:
 Magma intrudes between the horizontal layers of sandstone and shale that had formed over most S.A
 Magma cools and form horizontal sills
 Layers of sedimentary rocks are removed by weathering and erosion –sills of dolerite is then exposed
 Forming Karoo Landscapes with flat-topped hills.

13. Utilization of these landscapes by people
HILLY LANDSCAPES
HUMID
 Soils are more developed-agricultural activities
 Slopes are better drained due to vegetation cover and
contour ploughing-therefore limit soil erosion
 Heavy farming machinery will be limited on steep
slopes
ARID
 Slopes are more ragged
 Limited use of land due to less water and soils are
thinner
 Limited cultivation of slopes
 Large scale erosion due to lack of vegetation
 Grazing is more suitable

14. Continuation………
BASALTIC PLATEAUS
• Weathered basaltic rocks produces fertile soil rich in
iron
• Fertile soil and high rainfall-produce good agricultural
land
• High altitudes plateaus can experience low
temperatures in winter- not suitable for agricultural
activities
• Access to high plateaus will be limited and requiring
building of mountain passes which are expensive
CANYONS
• Steep sides and limited valley floor space-difficult to
farm
• Water on valley bottom not always accessible
• Form physical barriers as they are too wide to build
bridges across
• Tourist value due to beauty

15. Continuation…..
Karoo landscapes:
• Flat and easy for farming
• Flat and easy for building urban areas and transport routes
• Mostly in dry areas- Limit agricultural activities
• Soil is thin and rainfall is limited
• Rainfall in form of thunderstorms- sheet wash will increase run-off- no infiltration
• Large-scale sheep farming takes place
• Tourist destination

16. REFERENCES
Baer, G. (1991). Mechanisms of dike propagation in layered rocks and in massive, porous sedimentary rocks. Journal of
Geophysical Research: Solid Earth, 96(B7), 11911-11929.
Pettijohn, F. J. (1975). Sedimentary rocks (Vol. 3, p. 628). New York: Harper & Row.