O-LevelGeographyThe natural environment2217/12 · Oct/Nov 2014 · Q425 Marks

(a) Study Figs 6 and 7, which show information about the Mississippi River floods in 1993. [Figure 6] [Figure 7]

(a)(i)Name two states which were affected by the flooding in 1993.[1]
(a)(ii)Using evidence from Fig. 6 only, suggest two reasons why there was serious flooding at St. Louis. 1 2[2]
(a)(iii)Using Fig. 7, identify three methods used to try to prevent the flooding of the Mississippi River. 1 2 3[3]
(a)(iv)Explain why settlement and economic activity on flood plains is likely to increase the hazard of river flooding.[4]
(b)Study Photograph G (Insert), which shows a waterfall.
(b)(i)Describe the features of the waterfall shown in Photograph G. 1 2 3[3]
(b)(ii)Suggest what might happen to the waterfall in Photograph G in the future. Give reasons for your answer.[5]
(c)Describe and explain one of the following types of weathering. You may use a diagram. Carbonation Weathering process chosen ..................................................... Exfoliation[7]

This question uses a diagram from the original paper, which isn't shown here. Open the full paper from the past papers archive to see it.

Mark scheme

Marking points from the official mark scheme (Oct/Nov 2014). The mark or mark type is shown in brackets.

[1] (a)(i) Wisconsin/Minnesota/lowa/Missouri/Kentucky/Tennessee/Illinois/Kansas/Nebraska
[2] (a)(ii) It is a long way from the source/lower course; Many tributaries have joined together/just after a tributary/near a confluence/there are many tributaries; It is close to the river/on the flood plain/on flat land next to river; Large drainage basin/large catchment area.
[3] (a)(iii) Dams; Levees made higher; River straightening.
[4] (a)(iv) Building settlements on a flood plain puts more people at risk; Removal of vegetation/no roots to encourage throughflow; Reduces interception; More surface run off/less infiltration/less base flow; Silting of river bed; Large areas of concrete/impermeable surfaces; Artificial drains; Reduce lag time/water enters river more quickly; Loss of natural washlands.
[3] (b)(i) Ideas such as: Overhang; White water/fast flowing/rapids; Vertical drop/steep drop; Plunge pool/pool of deep water at base; There are two distinct steep sections; Bare rock/resistant rock/rocky/hard rock.
[5] (b)(ii) Ideas such as: Retreat of waterfall (upstream); Soft rock underneath hard rock; Soft rock worn away; Hydraulic action/splashback/abrasion; Hard form forms overhang/hard rock is undercut; Hard rock unsupported/collapse of overhang; Gorge forms. N.B.: Credit appropriate points on the diagram but do not double credit.
[7] (c) Levels marking Level 1 (1–3 marks) Statements including limited detail describing the process of exfoliation or carbonation. Level 2 (4–6 marks) More developed statements describing and explaining the process of exfoliation or carbonation. Level 3 (7 marks) Comprehensive and accurate statements, describing and explaining the process of exfoliation or carbonation. N.B.: Comprehensive coverage requires all stages of the process Level 2 Ideas Exfoliation: • Hot in the day/heating so rock expands • Cold at night/cooling so rock contracts • Stress in rocks causes the outer layers to peel • For L3 we are looking for the above developed statements with the idea of repetition of process over long period of time. Level 2 Ideas Carbonation: • Rainwater reacts with/absorbs carbon dioxide to form a weak carbonic acid • Limestone is made of calcium carbonate which is soluble • Rainwater lands on limestone and dissolves it to form a stronger carbonic acid or calcium bicarbonate • For L3 we are looking for the above developed statements with the idea of movement through joints and bedding planes speeding up the process. N.B.: Do not credit freeze thaw or any other weathering process. Highlight L3 statement when you have 3 × L2 statements.