Interesting holes in rocks: caves, potholes and tafoni

Lee, Chai Peng (2010) Interesting holes in rocks: caves, potholes and tafoni. In: Geological heritage of Malaysia: geoheritage conservation (1997-2009). Institut Alam Sekitar dan Pembangunan (LESTARI), Universiti Kebangsaan Malaysia, Bangi, Selangor, pp. 347-355. ISBN 9789675227370

Three main groups of interesting holes excavated by water and wind in rocks are caves, potholes and tafoni. Flowing acidic water dissolving parts of limestone creates most caves. Less common are lava caves in basalts and caves created by faulting and the collapse of overhangs in bedded rocks. Caves vary in size from gigantic caverns to small narrow tunnels less than a few centimetres across. Geological structures such as joints or faults and variations in mineralogical compositions of the limestone bodies control their shapes by differential erosion. Interesting speleothems like stalactites, stalagmites, pillars, curtains and gaur pools are formed by secondary calcite deposits in caves. Potholes are vertical rounded or oval pits eroded into rocks by sediment bearing vortices in rivers. Etch marks in isolated potholes in the granite of Telaga Tujuh in Langkawi indicate that direct dissolution of minerals by water can be a major contributor to pothole formation. Tafoni ("cave-like" in Italian) are pits of various sizes and shapes developed in granular or crystalline rocks such as sandstones or granites. They range in size from a few centimeters to several metres across. Larger ones are found usually in desert areas. Tafoni are created by the formation of a resilient duricrust of cemented rock followed by the development of pits by selected chemical weathering. Tafoni are developed on coastal outcrops by salt crystals precipited from dessicated sea water in the pores of the rocks that wedge out the less strongly cemented grains in the duricrust forming pits. Selective weathering enlarges them to create the beautiful typical honeycomb structures.

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Abstract

Three main groups of interesting holes excavated by water and wind in rocks are caves, potholes and tafoni. Flowing acidic water dissolving parts of limestone creates most caves. Less common are lava caves in basalts and caves created by faulting and the collapse of overhangs in bedded rocks. Caves vary in size from gigantic caverns to small narrow tunnels less than a few centimetres across. Geological structures such as joints or faults and variations in mineralogical compositions of the limestone bodies control their shapes by differential erosion. Interesting speleothems like stalactites, stalagmites, pillars, curtains and gaur pools are formed by secondary calcite deposits in caves. Potholes are vertical rounded or oval pits eroded into rocks by sediment bearing vortices in rivers. Etch marks in isolated potholes in the granite of Telaga Tujuh in Langkawi indicate that direct dissolution of minerals by water can be a major contributor to pothole formation. Tafoni ("cave-like" in Italian) are pits of various sizes and shapes developed in granular or crystalline rocks such as sandstones or granites. They range in size from a few centimeters to several metres across. Larger ones are found usually in desert areas. Tafoni are created by the formation of a resilient duricrust of cemented rock followed by the development of pits by selected chemical weathering. Tafoni are developed on coastal outcrops by salt crystals precipited from dessicated sea water in the pores of the rocks that wedge out the less strongly cemented grains in the duricrust forming pits. Selective weathering enlarges them to create the beautiful typical honeycomb structures.

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Item Type:	Book Section
Additional Information:	Available at Perpustakaan Sultan Abdul Samad, Universiti Putra Malaysia, 43000 UPM Serdang, Malaysia. QE299.5 G345 Call Number
AGROVOC Term:	caves
AGROVOC Term:	erosion
AGROVOC Term:	geology
AGROVOC Term:	geological surveys
AGROVOC Term:	geologists
AGROVOC Term:	preservation
AGROVOC Term:	sustainable agriculture
Geographical Term:	Malaysia
Depositing User:	Ms. Azariah Hashim
Date Deposited:	04 Feb 2025 07:45
Last Modified:	04 Feb 2025 07:45
URI:	http://webagris.upm.edu.my/id/eprint/1042

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