JJC_H2_GEO_P1_Ans

1 2018 H2 P1 Essay Question 1 a) Explain the characteristics of mass movement processes that occur in the tropics. [12] ** For mass movement types, possible types of mass movement that can occur in tropical regions:  Heave (although more prominent in the temperate regions, can occur in tropical regions when extreme changes in temperatures or alternate cycles of wetting and drying occurs) [Possible in AW climate types where there are temperature and rainfall variations throughout the year]  Flow (Common in Af and Am climates where high and intense rainfall events can occur)  Slides (Common in BS and BW climates where lack of vegetation could induce rock slides along slide plane). May also occur in AW or Am climates where rotational slips could occur in the presence of a curvilinear slide plane  Falls (common in all climate types where weathe ring causes lines of weaknesses to develop and once it gave way along areas of weaknesses, falls occur. ** Need to make some subtle link climatic types where mass movement types could occur. If students merely relate to characteristics w/o the links to the climatic types, maximum of 9 marks. Characteristics of Heave: Speed: Very slow (1mm to 1cm per year) Movement: Particles are lifted perpendicularly and dropped vertically Factors dependent on: Alternating cycles of expansion and contraction which can be attributed to large temperature changes, alternating cycles of wetting and drying Water content: generally low Key features: bent tree trunks, terracettes Material size: Varies from large to small Characteristic of flow: Speed: Generally fast Movement: Materials when incorporated with water, essentially moves as a semi-fluid mass Water content: Very high Factors dependent on: Water content (which determines speed and volume) Material size: Varies (from earthflow (mixed)to mudflow (generally fine)) Characteristic of Slide: Speed: Fast Movement: Along slide plane and in contact with surface Water content: low (may only be present to lubricate the surface Factors dependent on: presence of slide plane Material size: varies (Can be a rock or a consolidated mass) Characteristic of fall: Speed: Very fast Movement: Free fall through sky Water content: Low or absent Factors dependent on: Lines of weakness Material size: varies but usually rather large (rock falls)

2 b) The role of water is important in affecting the different mass movement types that occur in the tropics. Discuss the validity of this statement. [20] The role of water should never always be ignored in mass movements and that water certainly plays an important role in influencing the mass movement types as well as the rate at which mass movements occur in different tropical environments. This certainly means that the effects of water on mass movements should not be ignored. However, it must be noted that the role of water in various mass movement types differ very much