Keywords: 
• evaporate basin /
• paleoclimate /
• Late Pleistocene /
• Niel delta

Abstract: Stiff muds of the Late Pleistocene, revealed by 87 coriegs and tested by many sample analyses, are widely distributed in the entire former northern Nile delta plain. It is found on the basis of stratigraphic, lithologic, and petrologic analyses that there existed totally 14 lithosomes of stiff muds in the study area and four subfacies which are defined: Ⅰ)calcareous nodule bearing stiff muds, occurring constantly in the more outer of the all lithosomes, Ⅱ) gypsum nodule bearing stiff muds, emerging around the central sector of the almost all lithosomes, Ⅲ) shell bearing stiff muds, also distributed in central sector of the lithosomes and Ⅳ) plant debris bearing stiff muds, appearing less often. The distribution of subfacies of the stiff muds is closely related to alluvial processes. The characteristics of sediment components of stiff muds, such as calcareous nodule, gypsum nodule, jarosite, mollusk and Foraminifera, strongly demonstrate that the muds are of evaporate property within seasonally flooded alluvial sedimentary basins. Moreover, hot and dry weathers of the last period of Late Pleistocene are thus distinctively featured by the evaporate basins of stiff muds of the Nile delta, indicating the former semi-desertified Nile plain.