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Transcript
NANDI CENTRAL JOINT EXAMINATIONS – 2009 312/ 1 GEOGRAPHY PAPER 1 MARKING SCHEME. SECTION A 1. a) b) 2. a) Glaciation - Refers to the occupation, and sculpturing of the earth’s surface by the action of glaciers. 1x 1 = 1mk Factors that determine the rate at which glaciers move. Gradient of the land surface Friction Thickness and weight of glacier Temperature variations. 4x1=4mks Earth’s revolution Direction ✓ 1 Orbit ✓ 1 Sun ✓1 Total 3 marks b) Effects of Earths rotation. Causes day and night Causes deflection of winds and Ocean current Cause variations in Ocean tides Changes in time 3.a) Vegetation zones i) Q – Coniferous forest ii) R- Mountain vegetation iii) S – Desert vegetation b) Tree species found in Q Spruce Douglas fir / fir 1 2 x 1 =2mks 3 x 1 = 3mks Pine Larch 2 x 1 = 2mks 4. a) Climate change Establishment of new atmospheric / climatic conditions / climate in an area. 1 x 1 = 1mk b) Human causes of climate change Deforestation Industrialization Forest and grassland fires Cloud seeding 4 x 1 =4mks 5. a) Difference between a spring and a well. Spring is the point at which underground water finds its way onto the earths surface naturally where as a well is deep hole dug in the ground often with the purpose of getting water. 1x2= 2mks b) Sources of underground water. Rainwater Meltwater Lake and Seas water Man matic / plutonic water. SECTION B 6. a) i) Give the altitude of the lowest area or contour 3x1=2mks - 1480m ii) From the marginal information give the Magnetic variation as at January 1970. 2mks 1 2º31 west of true North b i) Across – section ✓1 between grid reference 540700 and 610700 Scale 1 : 50 ✓1 5mks c) Describe the relief of the area covered by the map. 5mks Generally it’s a high land area with highest contour . Lowest contour 1480m Generally the land rises from the NW towards the SE. The land slopes from the SE towards N/W Presence of river valleys drained by major rivers like Timbil, Kimungu. Presence of conical hills isolated. Any relevant point ( 1x 5 ) 5mks d) Citing evidence from the map, describe the climate of the area covered by the map 6mks 2 - The area receives heavy rainfall evidence by presence of forest (South Western forest/ evidence by presence of Tea growing –Tea estates e.g. Sambret / presence of many permanent River. The area experience cool temp evidence e.g. Tea growing – Tilvet Tea estate e) Economic activities 4mks Activity Evidence Crop farming Tea estate – Timbil Trading market e.g Kipsigirio market Transportation Roads e.g Processing Factory at Kericho tea estate V .S 1 : 5000 VE H .S 1 : 50,000 1 50,000 X 10 (bii) 5000 1 V .E 10 7. a) Aridity Process through which the soil experiences insufficient moisture leading to scanty vegetation or barren land. b) Reasons winds is a major agent of land sculpture in the desert. Deserts mostly consist of Sand and dust that are easily transported and deposited by wind. Deserts often are barren hence no vegetation cover in most areas hence wind easily picks the sand and dust. Moisture in the desert is insufficient therefore the soil is loosely binded and can easily be picked and transported by wind. Most deserts are expansive hence enough room for erosion and formation of dunes. 3 x 1 = 3mks c) Formation of features in the desert. i) Deflation hollows Wind blows over the desert surface and picks the loosened materials like sand through deflation. Continuously the materials are removed by rolling and lifting lowering the desert surface Eddy currents caused by the lowered surface continue to erode the depression widening it to form a deflation hollow. Depression begins to forms Direction wind Desert surface before erosion 3 Eddy current Deflation hollow Text 3mks Diagram 2mks Total 5mks ii) A barchan Is a crescent shaped mound of sand deposit often found in deserts Develops when sand accumulate on an intervening obstacle that lies in the path of the wind. Deposition starts with a Somali hill with prevailing wind to force some sand to move forward forming. Smooth gentle windward slope The effect at the wind eddies cause the formation of a steep slope and horns on the leeward side. Obstacles Prevailing wind Desert surface Sand deposits Prevailing winds Eddy winds 4 Horn Barchan Text – 3mks Diagram – 2mks Total 5mks d) e) f) i) ii) Characteristics of a seif dune Are ridge shaped / steep 1000m Lie parallel to the path at prevailing wind Long and extend to over looking Consists of corridors that are between 25 – 400m wide Factors influencing the transportation of material in the desert Strength and speed of wind Intervening obstacles / vegetation Nature of load Water mass / moisture weather changes Erosion features observed Rock pedestals Mushroom blocks Zeugeus Yardangs Deflation hollows Ventifacts Reasons for having a route map. Attend to all areas of concerned Avoid getting lost Estimate the total distance to be covered 3x1 2x1 8. a) Original Rock Metamorphic Rock Granite Gneiss Augite Horn blende Limestone Marble b) i) Name at least three rocks types that are found in Western Kenya. - Granite, Gneisss, Sandstone, Mudstone 1x3= 3mks c) Describe the formation of mechanically formed sedimentary rocks 5mks Pre – existing rocks are weathered to form sediments Sediments are then transported and deposited on land or on sea by water, wind or ice. Over a period of time they are consolidated into a hard rock due to pressure from the overlying material The layers of strata occur because of the change of composition of materials, particularly the size of the particles. 2 x 4 = 8mks d) Significances of rocks to man 6mks Some rocks form beautiful scenarier that attract tourists and hence earning country foreign exchange. Some rocks are used in building and construction e.g, limestone and granite. Some are raw materials e.g limestone to the cement industry, trona – Magadi Sand is a source of building material 5 Fossil fuel- coal is associated with sedimentary rocks. Any relevant point 6mks e)i) Methods of data recording 2mks Photograph taking Drawing sketches Filling in tables / tabulation Writing notes Any relevant 1 x 2 = 2mks ii) Importance of a route map 3mks To save time To ensure every activity is given ample time. Estimate the cost of the study 9.a) Folding -Process of crustal distortion that often causes rocks to bend upwards or downwards.1x1mk b) Major fold mountains of the world A – Appalachians mts 1x1 B- Rochies 1x1 C – Ural mts 1x1 D- Caps ranges 1x1 c) Formation of fold mountains under the following theories. i) Contraction theory Initial cooling of the earth, the outer surface cooled and contracted faster than the interior Surface rocks started wrinkling inorder to fit on the cooling and contracting rocks of the interior. These wrinkles formed the present fold mountains 3 x1 mks ii) Convectional currents theory Movement of convectional currents in the mantle horizontally causes a frictional drag on that crustal rocks forcing them to move. When continental coast are pulled towards each other they force sediments between them to fold Folding of such sediments leads to formation of folds that have often caused the formation of fold mountains. (3x1marks) d) Significance of folding to look physical and human environment. Fold mountains often facilitate the formulation of relief rainfall hence windward sides of such mountains experience heavy rainfall while the lee ward often relieve little or no rainfall. Most fold mountains often act as water catchments areas as some contain glaciers, that can lead to melt water whereas others are sources of rivers especially on the windward side. In some fold mountains Katabatic winds often are cold and cause harm to crops especially in the lower valleys and slopes. Process of folding could bring minerals to the surface marking the exploitation of such minerals cheap. Fold mountains provide unique scenery that act as a tourist attraction hence as the country earns foreign exchange Fold mountains at times act as barriers to transport and communication especially if it lacks passes. Mountains areas often dissauge settlements hence most f such areas are un inhabited. 6 Any 3 x 2 mks c) Formation of Rift Valley by tensional forces. Crustal rocks are subjected to tensional forces Tensional forces Continued subjection of tensional forces to crustal rocks leads to development of normal fault lines. Fault line Fault line Development of two faulting divides the crustal rocks into three major blocks. The centre block subsides as the two side blocks are pulled by tensional forces. This results to the formation of a trough called a rift valley. Rift Valley Diagram – 3mks Text – 3mks T – 6mks d) Features resulting from faulting Rift valley Escarpment / faultscape Fault blocks or Block mountains Tilt blocks Any 2 x 1 mks 10. i) Define the term mass – wasting 1mk Mass – wasting is the downward movement of weathered material under the influence of gravity. ii) Three types of rapid mass – wasting 3mks Rock slump, Rock slide, Rock slide, Rock fall, and avalanche. b) Three ways in which soil creep occurs 6mks Due to temperature changes soil particles expand and contract hence shift position down slope Moisture in the soil causes it to become wet and compact on drying, the particles loosen and shift position down slope. Frost hearing beneath soil particles lifts particles at high angles to the slope but they fall back perpendicularly under gravity 7 c) d) Extend forces like earth quakes, explosives in mining or heavy vehicles trigger off the movement. 2x3 Identify four underground features found in a karst Scenery 4mks Stalagmite, stalactite, pillars, caves 1 x 4 = 4mks Formation of stalagmite 6mks Diagram – 3mks Text – 4mks Limestone rock Under ground stream Stalegmite Rainwater dissolves carbon dioxide as it passes through the car to form weak carbonic acid. The rainwater dissolves calcium carbonate as it percolates through limestone joints The solution in form of calcium hydrogen carbonate drips to the floor of the cave. Some of the water and carbon dioxide are released leaning behind deposits of calcium carbonate. The calcium carbonate deposits grow upwards from the floor of the caves to form finger like projections called stalagmite. Conditions necessary for the formation of Karsts scenery 5mks The rock below should be limestone, chalk or dolomite. The rock should be well jointed soluble allowing solution to occur along the joints. The region should receive moderate high rainfal to facilitate solution process. The watch table should be deep to allow water percolation and sub sequential erosion Warm / hot climate. - e) 8