Geology Reference
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70 m. Each is 2-3 m high. Both follow along major sheeting joints and appear to be due to the
weathering of the granite by moisture, with the greater part of the cave development taking place
on the underside of the upper sheets (Fig. 10.2).
Boone's Cave, in North Carolina, USA, is similar. Developed in a granite-gneiss, it is some
40 m long, displays obvious joint control in plan, and is thought to be essentially an enlarged bed-
ding plane. Similar fracture-controlled caves in granitic rocks, and totalling some hundreds of
metres in length, are developed in California, and an opening, some 35 m long and aligned paral-
lel with the hillslope and a sheet fracture, is reported from near Seoul, in South Korea.
(b)
Figure 10.1.
(b) Cave formed along sheet fracture, Enchanted Rock, central Texas.
(a)
Figure 10.2.
(a) Tafone developed on a parallelipipedic block of granodiorite in Monte Louro, Galicia, NW
Spain.
