FORMATION OF GYPSIC HORIZONS IN SOME ARID REGIONS SOILS OF JORDAN

Abstract

This paper reports on the formation of soils with gypsic horizons in Quaternary sediments in arid regions of Jordan. Gypsic horizons were formed from eolian and alluvial sediments as well as through in situ weathering of sandy parent material. The gypsum originated from the parent rock found in that area. The formation of the gypsic horizons seems to have formed under a climate slightly more humid than the present one. Present soil forming processes seem to favor the formation of salic horizons without any influence of ground water or saturation. Apparently, wetting of upper soil layers for very short periods of time, and the dominance of sandy soils and dry climate, are responsible for the upward movement of soluble salts. Suggestions are made to account for the occurrence of gypsic horizons in shallow soils and in soils derived from different sediments in the classification of Aridisols at the subgroup level. Use of the term lithic is proposed for shallow soils with gypsic horizon, while the terms fluventic and eolic are proposed for the classification of Gypsiorthids influenced by fluvial and eolian activities, respectively. It is also proposed that saturation be waived as a requirement for recognition of salic horizons in Aridisols.