Page 170 - Fundamentals of Geomorphology

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WEATHERING AND RELATED LANDFORMS

The decomposition and disintegration of rock is a primary process in the tectonic cycle and landscape evolution.
This chapter covers:

weathering waste
weathering landforms
the global pattern of leaching and weathering
weathering and buildings

Weathering in action: the decay of historic buildings

The Parthenon is a temple dedicated to the goddess Athena, built between 447 and 432 BC on the Acropolis of Athens,
Greece. During its 2,500-year history, the Parthenon has suffered damage. The Elgin Marbles, for example, once
formed an outside frieze. Firm evidence now suggests that continuous damage is being caused by air pollution and
that substantial harm has already been inflicted in this way. For example, the inward-facing carbonate stone surfaces
of the columns and the column capitals bear black crusts or coatings. These damaged areas are not significantly
wetted by rain or rain runoff, although acid precipitation may do some harm. The coatings seem to be caused by
sulphur dioxide uptake, in the presence of moisture, on the stone surface. Once on the moist surface, the sulphur
dioxide is converted to sulphuric acid, which in turn results in the formation of a layer of gypsum. Researchers are
undecided about the best way of retarding and remedying this type of air pollution damage.