Unit 5 Forms of Relief.pdf
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This document defines key concepts related to landforms and relief features. It discusses different types of slopes like concave, convex, gentle and steep slopes. It also defines concepts like altitude, contours, and different types of continental relief features such as mountains, hills, plateaus, ridges and valleys. Marine relief features of the ocean floor are also explained, including continental shelves, slopes, rises, trenches and abyssal plains. Examples are given for many relief features. The document concludes by discussing the relationship between different relief features and human activities.
Unit 5 Forms of Relief.pdf
- 1. UNIT 5: FORMS OF RELIEF
- 2. LEARNING OBJECTIVES In this unit, the learner will be able to: •Define relief. •Identify the different forms of relief. •State the relationship between relief and human activities.
- 3. SLOPE, ALTITUDE AND CONTOURS ❖ Slope: is the rise or fall of the relief feature. It is a measure of the degree of inclination of a feature in relation to the horizontal plane. Slope is determined by the angle of elevation. Slopes are classified in the following types: a) Concave slope b) Convex slope c) Steep slope d) Gentle slope
- 4. TYPES OF SLOPES a) Concave slope: this is a slope that has a steep section uphill and a comparatively gentle section downhill. It is known as waning slope b) Convex slope: this is a slope that is more or less gentle uphill but comparatively steeper downhill c) Gentle slope: this is a slope which is almost flat. Its elevation is flat compared to the convex, concave, and steep slopes. d) Steep slope: this is a slope that is almost vertical or relatively high gradient. Gradient: refers to steepness or gentleness of an area. Even slope: is the term which is used when there is uniform change in gradient between two points on the earth’s surface.
- 5. Steep slope
- 6. ALTITUDE Altitude: this is the height or elevation of a point above a given reference point. The reference point is the sea level which is at a zero meter. Altitude is expressed in feet or meters. Therefore, altitude is defined as the height above the sea level.
- 7. CONTOURS A contour: is a line connecting points (places) of the same altitude on a topographical map. Contours show the type of relief on the earth's surface. Interpretation of contours ✓Contours appearing close to each other represent Steep Slope ✓Contours spreading over a large area represent Extensive Plain ✓Contours forming concentric circles represent Hill or Mountain ✓Contours appear to overlap or cross each other represent Cliff ✓Contours are V or U shaped represent Valley.
- 9. FORMS OF RELIEF FEATURES Relief features are classified into two main categories. These include a) The continental relief features b) The marine relief features These relief features had been formed by both internal and external forces: The internal forces such as: • Tectonic plate movement, • Vulcanicity, • Earthquakes, The external agents such as: • Winds, ice, • Rain leading to mass wasting and • Erosion and deposition. Vulcanicity as cause of major relief features
- 10. CONTINENTAL RELIEF FEATURES The main forms of continental relief include the following: a) Mountain: is a very large landform that rises above the area surrounding it. It usually has a peak. Mountains may appear as single landmass or in a chain called range. Example mountains are: ❖ Mount Everest (8,848m) in Tibet (China-Nepal) found in Himalaya ranges. it is the highest peak mount in the world ❖Mount Kilimanjaro (5,895m): It is found in Tanzania. It is the highest peak mountain in Africa ❖Mount Karisimbi (4,507m): The highest peak mountain in Rwanda ❖Mount Aconcagua (6,960m): The highest peak in South America located in Andes Mountain range in Argentina ❖Mount Denali (6,144m): The highest peak in North America located in Alaska range in USA.
- 11. Mount Denali 6,144m Mount Aconcagua 6,960m Comparison of mountains in the world Himalaya mountain range is located in Asia and is known to have highest mountain peaks in the world Himalaya mountain range is located in Asia and is known to have highest mountain peaks in the world
- 12. TYPES OF MOUNTAINS Mountains are classified into the following types: ❖Block mountain: these mountains form due to the process of faulting. For example, Mount Rwenzori (5,111m) in Uganda and DRC border ❖Volcanic mountains: these mountains forms due to the process of vulcanicity (volcanic eruption), for example: Mt Elgon (4,321) between Kenya and Uganda. ❖Fold mountains: these mountains form due to the process of folding. For example; ❖Atlas range in northeast and Cape range in southeast of Africa ❖Himalayas in Asia ❖Andes mountain range in South America ❖Rockies in North America ❖Inselberg: these mountains form due to erosion, and accumulation of snow and ice on the continent or sea/ocean.
- 14. b) Hill: this is a landmass that extends above the surrounding terrain. However it is smaller than a mountain c) Plateau: is a raised land that is almost flat at the top with gentle slopes on all sides to the lower ground. For example, the central plateaus of Rwanda, and the eastern African plateaus in Africa. d) Ridge: this is a linear, steep-sided upland. It is a relief feature that consists of a chain of hills or mountains. e) Escarpment: This is a steep slope that separates an area of high ground from an area with lower ground. f) Spurs: this is an area of high ground that sticks out of a mountain hill
- 16. g) Plain: this is an extensive area tract of flat land. Plains are categorized into: ❖Peneplains: these form due to the wearing down of lands that were once much higher. For example: Karamoja, Soroti in Uganda ❖Alluvial (flood) plains: these form due to the accumulation of silts brought down by rivers. For example; Nyabarongo plain ❖Coastal plains: these form alongside the coast due marine deposition. For example, Rufiji Delta on the coast of Tanzania Flood Plain on Nyabarongo river
- 17. h) Valley: This is a low area of land between hills or mountains, typically with a river or stream flowing through it. There are two types of valleys: ❖U-shaped valleys: these valleys are found between hills with gentle slopes. ❖V-shaped valleys: these valleys are found between mountains with steep slopes. U Shaped Valley V Shaped Valley
- 18. MARINE RELIEF FEATURES These are landforms that are found on the oceanic crust. They include beaches, gulfs, cliffs, and capes. Beaches Gulf of Mexico Cliff Cape
- 19. The main relief features of the ocean bed
- 20. 1. Continental shelf: is an underwater landmass extends from the shorelines towards the ocean deep. This region represents 7.5% of the total ocean area. Continental shelves are wide in Japan, Canada, U.S.A but narrow in Africa. 2. Continental slope: this is a steep slope that extends from the edge of the continental shelf to the deep ocean plain. It consists of mud, and silt, and is often cross cut by submarine canyons. It is widely 20kms.
- 21. 3. Continental rise: is an underwater feature found between the continental slope and the abyssal plain. 4. Continental ridge: this is a submarine mountain formed from ocean volcanic eruption. For example, • East pacific ridges, • Atlantic mid-ocean ridge, and • Mid-Indian ocean ridge.
- 22. 5. Oceanic trench: this is long narrow steep-sided depression in the oceanic crust. It is the deepest part of the ocean. For example, • Marianna trench in Pacific Ocean with 10,994meters below sea level. • Java trench in Indian ocean, • Tonga trench in Pacific ocean, • Peru-Chile trench in Pacific Ocean • Atacama trench in Pacific ocean
- 23. 6. Abyssal plain: is underwater plain on the deep ocean floor which is usually found at depths between 3,000 and 6,000meters. It extends from continental rise to mid-ocean ridge. It therefore covers 50% of the earth’s surface.
- 24. 7. Oceanic island: is that rises to the surface from the floor of ocean basins. Oceanic islands are formed by the continuous eruption with oceans. When these oceanic islands are eroded, it results in formation of guyots. Examples: • Azores, Ascension and Saint Helena islands in Atlantic ocean, • Hawaiian islands in Pacific ocean. • Madagascar island in Indian Ocean Mnemba Island of Zanzbar in Tanzania
- 25. FIGURES SHOWING MARINE RELIEF FEATURES
- 27. RELIEF FEATURES AND HUMAN ACTIVITIES ❖Hill tops favour the construction of telephonic communication masts ❖Gentle sloping areas favour farming, construction of roads, and settlement ❖Flat valleys promote rice, sugarcane and vegetable growing because of the presence of water in them ❖Plains tend to favour cattle rearing, construction of railway lines, and aerodromes, etc……. ❖Mountainous areas promote forestry which later favours lumbering and attraction of tourists ❖Steep slopes hinder farming, transport and communication development. ❖Steep slopes are less exploited because it demands high capital