Geology Reference
In-Depth Information
Figure 9.21.
Font, some 4 m high, in granite, Sierra Guadarrama, central Spain (Centeno, 1988).
to preferential etching and can be explained in terms of weathering and erosion of the areas adja-
cent to basins. As the surface around the doughnuts is lowered, they develop fonts when the diam-
eter of the crestal basin is less than its height above the adjacent platform. Every stage in this
process of lowering of the surface surrounding basins can be seen at some localities in the Serra
do Gêrez (Coudé Gaussen, 1981) and the Sierra de Guadarrama, both on the Iberian Peninsula.
REFERENCES
Blank, H.R. 1951. “Rock doughnuts”, a product of granite weathering. American Journal of Science 249,
822-829.
Boyé, M. and Fritsch, P. 1973. Dégagement artificiel d'un dôme crystallin au Sud-Cameroun.
Travaux
et Documents de Géographie Tropicale
8: 69-94.
Centeno, J.D. 1988. Morfología Granítica de un Sector del Guadarrama Occidental (Sistema Central Espa
~
ol).
Editorial, Universidad Complutense de Madrid.
