Most of the limestones in the Eocene Carbonate plateau, west of the Nile Valley (Sohag), are affected repeatedly by karst processes, and different landforms related to limestone dissolution occurred. However, there is no published literature available dealing with the detailed studies of the karstification process and associated karst landforms in this study area. Therefore, this study focuses on paleoerosion surfaces and evolution of the landscapes of the Eocene carbonate plateau, and discussing the factors controlling the development of karst features, and their evolution, as well as presents the associated natural hazards and their impacts. By
integrating geomorphological, and sedimentological techniques,, the karstic carbonate rocks west of Sohag were subjected to three deep weathering cycles that probably started after the Eocene uplift and continued up to Late Miocene. This has led to the continuous lowering of the landscape of the plateau and the generation of three paleoerosional surfaces of different altitudes with distinct karst features developed from the Late Eocene through the Miocene, termed here as S1 to S3. Surface S1 considers a part of a planation surface named Western Plateau surface, developed in the late Eocene age during a fall in sea-level, dominated by calcrete hardpan, fluvio-karst features and flutings. S2 occurs at the top of the widely nearby plateau escarpment that took place during the Late Oligocene-Miocene age. This surface is marked by a widespread of surface and subsurface solution features and landforms, ranging from cone karsts and ridges grades to karrens, and is covered by the deeply entrenched valleys, paleodolines and caves. Paleodolines. range from solution type formed at the early-stage dissolution to collapsing-sagging created by large solution cavities with associated raveling of the overburden, to stable sediment in-filled, buried paleodolines. S3 was formed during the lowering base level of the Mediterranean during Messinian Salinity Crisis in Late Miocene age and was synchronous with the onset of incision of the Nile channel. This surface is characterized by an undulating relief interrupted by deep downcutting canyons and its infilling during the Plio-Quaternary Nile sediments.
The karstified limestone in the investigated area was affected by ground instability such as paleodolines and irregular rockhead, floods, slope failures and landslides. It believed that the low-gradient topography and subhorizontal bedding, paleoclimate , deformational structure, fluvial processes and the soluble rock lithology seem to be the main controlling factors the dissolution-induced landforms. and associated hazards and evolution of landscape. Finally, the understanding of characteristics and the occurrences of the active paleokarst features in these karstic areas is useful in identifying the possible geoenvironmental impacts and the causes of ground subsidence to structures during urban development