arising from expansion and contraction, wetting and drying and from the effects of repeated freezing and thawing (Smith and Collis, 2001). As
Beaumont (1972) noted, due to the lowering of mean temperature in
Iran during glacial periods of the Quaternary, frosts would be of more
common occurrence during the winter months, and the lower winter
temperatures would mean that snowfall would occur more often than
at the present day. It is most likely that the study area has had wetter
and colder climate during glacial periods and hence it is reasonable to
expect that the physical weathering has been more intense in glacial periods than in the present-day climate. Although the chemical decomposition is almost lacking at the present-day interglacial period, it is likely
that chemical weathering has been developed to some extent during
colder and wetter glacial periods.