The diagram shows a limestone hillside in the Margalla Hills after rainwater has entered cracks in the rock. A conservation group is preparing a trail guide...
Question 1 Report
The diagram shows a limestone hillside in the Margalla Hills after rainwater has entered cracks in the rock. A conservation group is preparing a trail guide that explains why caves, springs and thin soils occur in this landscape. The group also wants visitors to understand the limits on development in such an area.
(a) Name the rock type shown in Fig. 1. [1]
(b) Describe how the cave labelled X can form. [2]
(c) Explain three difficulties that this landscape may create for construction. [3]
Answer Details
(a) Limestone [1] (b) Rainwater absorbs carbon dioxide and becomes weakly acidic [1]; it dissolves limestone along joints/cracks until a cavity enlarges into a cave [1]. (c) Any three: uneven ground and underground voids cause instability/subsidence [1]; thin soils give poor foundations [1]; water drains underground so reliable surface supply may be limited [1]; steep slopes increase excavation costs [1]; caves/springs may require environmental protection [1]. [3]
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