Geology Reference
In-Depth Information
The caves run for some 60-70 m between corestones. These caves appear to be due to the piping
and flushing of grus. The corestones and grus either remain sufficiently rigid to form a roof and
sidewalls, or the corestones subside toward the evacuated area, but are packed closely enough to
jam together and form a roof of reasonable stability.
Again, some ten granite caves, varying in length between two and fifteen metres, have been
reported from the High Tatra Mountains of Poland. Some appear to be of the same origin as those
already considered, but others are attributed to preferential solution acting along sideritic veins.
There are also vertical shafts and niches in the Karkonosze Mountains, also in Poland, where they
are associated with feldspar-rich zones. Calcite speleothems are developed on the ceilings of some
of these caves, and also in caves in the Spanish Pyrenees, in Lleida Province (Vidal Romaní and
Vilaplana, 1984), or in Andringitra Massif, Madagascar, where the dissolution of plagioclase provide
calcium (Vidal Romaní, Twidale, Bourne, 1998).
10.3
CAVES ASSOCIATED WITH FRACTURES
Weathering along sheeting planes has in many places created gaping partings. At a few sites such
weathering has proceeded to such an extent that the openings are large enough to be called caves.
Thus, the Enchanted Rock caves, located on the bornhardt of the same name in the Llano of central
Te xas, are developed at two levels (Fig. 10.1). The upper cave is some 250 m long, the lower about
(a)
Figure 10.1.
(a) Plan of caves at Enchanted Rock, central Texas.
