This leaves a wide depression at the top of the volcano called a caldera 10 a

This leaves a wide depression at the top of the

This preview shows page 88 - 91 out of 172 pages.

- This leaves a wide depression at the top of the volcano called a caldera 10. a) - It is a theory that states that the crust is divided into blocks of land (plates) that float and move towards, away or parallel b) - Compressional boundary - Extension boundary - Transform fault boundary c) - Geological evidence – Rock similarities in structure, age and type of rocks found in various continents e.g. in Eastern coast of S. America and Western coast of Africa
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- Jig- saw- fit – of continental coastlines. Some coastlines can fit each other when pulled together e.g. Western coast of Africa can fit with Eastern coast of South America - Ancient glaciations – All the four Southern continents reveal signs of a period of large scale glaciations at one time. It is evidenced by presence of glacial deposits – Tillites produced by ice sheets in Southern continents - Archeological evidence – Some plant and animal remains found in various continents show a striking similarity 11. a i) - Atlas - Cape ranges - Akwapim ii) - Atlas - Cape ranges - Akwapim iii)- Symmetrical folds have limbs dipping uniformly about the axis while asymmetrical fold one limb is steeper than the other about the axis . b i) b i) - Extensive shallow depression called geosynclinal develop - Sediments from high areas are deposited in the geosyncline - Compression on either side push towards geosyncline - Sediments compress to form fold mountains which rise above sea level to form fold mountains b ii) - Over fold - Recumbent folds - Nappe or overthrust fold - Anticlinical/ synclinal fold - Isoclinal 12. a) - Causes seasons - Varying lengths of day and night time - Changes in the position of the mid-day sun at different times of the year - Causes eclipses b) - Movement of magma within the crust - Gravitational force towards the center of the earth - Convectional currents in the mantle - Isostatic adjustment of sial and sima layer SIAL MANTLE geosyncline seen SIAL Compression SIMA Sea Fold mt. Fold mt. SIMA
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13. a) - Frequent earthquakes - Presence of faults - Presence of fold mountains b) - Tectonic movements - Volcanicity - Gravitative pressure - Isostatic adjustment - Energy release in the mantle 14. a) - Nature and age of the rocks - Intensity of compression forces . b) - May cause a river to disappear - Changes the rivers direction of flow - Forms depressions hat are filled with water forming lakes - Faulting across a river forms waterfalls 15. a) - The jig-saw fit√ - Glaciatean/ancient glaciation√ - The coal deposits√ - Sea floor spreading√ b i) - Australia√ - South Africa√ ii) this was the water body that occupied the region surrounding the pangae 16. a) - High demand for hard wood has led to over exploitation - They take long to mature hence can not match the exploitation rate - Population pressure has led to cutting trees to give room for settlement and agriculture b) - Accidental fires which destroy the forests - The Northern part is inaccessible (during winter) for exploitation of the forests - Over exploitation in some areas - Trees take long to mature due to cold climate - Rugged landscape especially mountainous landscape makes exploitation difficult 17. (a) i)
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