SOIL-MORPHOLOGY IN THE STUDY OF CLIMATE CHANGE IN A SEMI-ARID REGION OF NORTHWESTERN IRAN
harged on “global warming”, and held responsible for the shortage of water. In a study in northwestern Iran, geopedologic investigations, In the past few decades, changes in climatic conditions, particularly in (semi-) arid regions, are csupported by soil micromorphological study and
some archaeologic data, were projected in the historic framework to reconstruct landscapes, since several millennia, through which changes of climate could be deduced. The occurrence of a vast layer of travertine, formed around 27,000 years B.P. in a rich karstic environment, coated by an organic matter containing layer, with some rancienite mineral, dated back from 13,000 B.P., implies a humid environment, corresponding with the uppermost Wűrm, a pluvial period. The geopedologic surveys supported by soil micromorphology revealed that between 6,000 and 2,600 years ago the area was subject to cycles of erosion and sedimentation leading to the formation of glacis. An arid type of climate characterized by the alternation of wet and dry periods is also supported by the occurrence of petrocalcic and argillic horizons. Although the climate has further turned dryer, cultivating rice, tobacco and cotton, which is said to have been stopped a few centuries ago, implies a wetter condition than today. The study concludes that the change in soil moisture regime (aridification) has never been as degrading as it is today, due to the over-exploiting of the non-renewable fossil groundwater.