A coastal engineer used aerial photographs to prepare Fig. 1 for a resource booklet about a rapidly retreating boulder-clay coast. The two cliff outlines ar...
Question 1 Report
A coastal engineer used aerial photographs to prepare Fig. 1 for a resource booklet about a rapidly retreating boulder-clay coast. The two cliff outlines are from the same 1 km section of coastline, photographed in 2006 and 2026. The engineer will use this study figure when deciding whether a small caravan site behind the cliff needs protection. North is towards the top of the figure. The arrows show the direction of prevailing waves approaching the beach.
(a) Identify which cliff line, 2006 or 2026, is nearer to the caravan site. [1]
(b) Describe the change in cliff position shown in Fig. 1. [2]
(c) State two reasons why boulder clay is likely to retreat quickly when exposed on a coastal cliff. [2]
(d) Explain how the engineer could use fieldwork to obtain more reliable evidence about the rate of cliff retreat. [5]
Answer Details
(a) The cliff line nearer the caravan site is the 2026 line. [1]
(b) The cliff has moved landwards, by about the width between the plotted lines, approximately 35 m. [2]
(c) Boulder clay is weak and unconsolidated, can be easily saturated by rain, has few resistant layers and is prone to slumping. Any two reasons gain credit. [2]
(d) Measure fixed distances from permanent markers using a tape or GPS. Repeat measurements at several sites along the coast and at regular dates over years. Use the same method and locations each time, then photograph or map results so change can be compared accurately. Repetition and consistency make evidence of retreat more reliable. [5]
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