Mountain Landforms and Geomorphic Processes - Mountain Geography: Physical and Human Dimensions - page 235

Chemical Weathering
Very little research has been done on the role of chemical weathering in mountains. This
is not only because of the apparent dominance of frost action, which tends to mask the
more subtle effects of chemical action, but also because of the difficulty in measuring
and studying chemical processes. Chemical weathering requires the compounds to be
in solution and a certain amount of heat to be supplied for a chemical reaction to occur.
Therefore, Peltier (1950) and others thought it was simply too cold and arid when water
is frozen in deserts, polar regions, and most mountaintops for chemical weathering to
occur (Fig. 5.4). Mountains in the humid tropics or near oceans generally show more
active chemical weathering than mountains in continental and arid regions. There is
also evidence of some chemical weathering even in arctic and continental mountain cli-
mates (Washburn 1980). Certain types of chemical processes such as carbonation (the
alteration of minerals that contain basic oxides to carbonate salts by action of carbonic
acid) may actually be accelerated in cold climates because of the greater solubility and
concentration of carbon dioxide (CO 2 ) at low temperatures (Caine 1974). Furthermore,
snow meltwaters are acidic; therefore, chemical weathering must play an important role
in the alpine environment (Gerrard 1990).
FIGURE 5.4 Chemical surface weathering of a rock in the Sangre de Cristo Mountains of Colorado.
Note the hollowed depressions on the face of the rock. (Photo by J. R. Janke.)
Although reduced temperatures hinder chemical weathering, glacial activity can en-
hance chemical weathering by providing fine sediment that is easily weathered, as well