The diagram below represents underground features in a limestone area. Use it to answer question (a)

KCSE Geography Paper 1 2009 Section B Question 10.

The diagram below represents underground features in a limestone area. Use it to answer question (a)

​(a) (i) Name the features marked X, V and W 

• X-Stalactite
• V-Stalagmite
• W-Cave

(ii) Describe how the feature marked Y is formed 

• Solution of solution carbonate trickles down slowly through the roof of a cave/ cavern
• Solution droplets hang on the roof of the cave
• Water evaporates and calcium carbonate it is precipitated
• The precipitated calcium carbonate gradually builds downwards over a period of time as the solution continues to drip from the roof. This forms a stalactite
• The solution splashes on the floor and water evaporates
• The calcium carbonate in it precipitates and gradually builds upwards to form a stalagmite.
• Over time, the stalactite and the stalagmite join to form a pillar/ column

​(b) (i) What is an artesian basin? 

• It is a saucer – shaped depression consisting of layer of permeable rock lying between two layers of impermeable rocks, with part of permeable rock exposed to the surface along the edges of the basin.

(ii) Explain three factors which influence the formation of features in limestone areas 

• The surface rock must be thick limestone to allow solubility by rainwater
• The rock should be hard and well jointed to allow water to percolate through the lines of weakness
• The climate should be hot and humid to facilitate chemical reaction/ weathering/ carbonation.
• The water table should far below the surface to allow for the formation of the features 

​(c) You are supposed to carry out a field study of an area eroded by water
(i) Give three reasons why you would need a map of the area of study 

• To show the extent/ delimit the area of the study
• To show the route to be followed during the study
• To show drainage features 
• To be able to estimate distances
• To show the general nature   of the terrain

(ii) Name two erosional features you are likely to identify during the field study 

• Exposed rocks 
• Ridges / clients
• Gullies/ wades/ grikes/ dry river bed
• Earth pillars

​(iii) State three recommendations that you would make from your study to assist the local community to rehabilitate the eroded area

• Building of gabions
• Constructing of terraces
• Planting trees
• Adapting farming methods that allow conservation of soil. i.e. planting of over crops / mulding/ strip farming.

Related Geography Searches on  Action of Water in Limestone areas Form 3 Level

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