Fig. 1 shows a geological cross-section of a small coastal bay between two projecting headlands. The headlands are made of resistant granite, whereas the ce...
Question 1 Report
Fig. 1 shows a geological cross-section of a small coastal bay between two projecting headlands. The headlands are made of resistant granite, whereas the central section contains softer mudstone. Students on a fieldwork visit recorded wider beaches in the bay and steep cliffs on the granite. This study figure helps explain why a coastline made of alternating rock types has an irregular outline. The wave arrows indicate waves reaching the coast from the south.
(a) Identify the rock type that forms the headlands. [1]
(b) Describe the coastline shape created where softer mudstone is eroded. [2]
(c) State two characteristics of granite that make it more resistant than mudstone. [2]
(d) Explain how differential erosion produces the pattern of headlands and bays shown in Fig. 1. [7]
Answer Details
(a) The headlands are made of granite. [1]
(b) Faster erosion of mudstone creates a bay or recess, set back between the projecting headlands. [2]
(c) Granite is hard, well consolidated, resistant to erosion and generally has fewer weaknesses or joints than softer rock. Any two characteristics gain credit. [2]
(d) Waves erode all parts of the coastline, but softer mudstone is removed more quickly, forming a bay. Granite erodes slowly, so it remains projecting as headlands. Wave attack is focused on the sides of headlands, whereas water in the bay is more sheltered. Lower wave energy in the bay encourages sediment deposition, producing a wider beach. [7]
Download The App On Google Playstore
Everything you need to excel in your exams
