Origins of Mountains - Mountain Geography: Physical and Human Dimensions - page 43

Africa, and South America are the best known. The famous Ayers Rock (Uluru to the Ab-
original Australians) is such a remnant, consisting of Precambrian sandstone. In Africa
and South America insel-berg (German for island mountain) landscapes abound. Where
near-vertical regional joints in the bedrock are widely spaced, curved sheeting joints
that crudely parallel the Earth's surface can cause isolated, solid-rock inselbergs to de-
velop smooth, domal bornhardt or sugarloaf shapes. Half Dome in Yosemite National
Park and the great Sugar-loaf Mountain with the colossal Christ figure in the harbor
of Rio de Janeiro, Brazil, are examples. Where regional and sheeting joints are closely
spaced and strongly weathered, corestones develop; tors or castle koppies (kopje) also
result from stripping away of weathered saprolites.
FIGURE 2.14 The direction of prevailing winds over a mountain range can have profound effects be-
cause of the effects of orography. Mountains lift the air flowing over them, causing strongest pre-
cipitation on the windward side. This causes maximum erosion on that side, with the consequent
exposure of the most deformed and metamorphosed rocks there. The growth and exhumation of
mountains are thus affected differently, depending upon whether the direction of subduction and
prevailing winds are in the same or the opposite direction. (After Willet et al. 1993; Pinter and
Brandon 1997; Keller and Pinter 2002.)