From Late Eocene to Holocene, the Egyptian Nile Valley has been subjected to six stages (or phases) of geological evolution which considered as a reflection of intensive tectonic events took place in the neighboring sedimentary basins (e.g. NE-Africa basin, the Eastern Mediterranean basin and Red Sea basin uplifting). Consequently, the geological setting of Upper Egypt generally can be considered as a representative model in which all evolutional stages of Egyptian Nile Valley were typically represented. The Paleonile Clays (Pliocene) are widely distributed in Upper Egypt as surface and subsurface sequences. These fine-grained clayey-sediments are affected negatively on construction activities owing to their highly swelling potentiality. Montmorillonite represents an essential component of clay mineralogy of Paleonile Clays with others (illite-montmorillonite mixed-layer, kaolinite, illite and trace amount of chlorite). The Exchangeable Sodium Percentage (ESP) values of Paleonile Clays are very low additionally its plasticity index values are exceeded than 35%. This indicated that the studied Paleonile Clays are swell-able clay type (non-dispersive type) and its dispersive ability is not significant. The Paleonile Clays (Pliocene) micro-fabrics are dominated mainly by flocculation and aggregation fabric types, which had relatively higher swelling potentiality. The swelling potentiality of the studied Paleonile Clays has strong relations with clay-sized fraction (%), montmorillonite (%), plasticity index (PI) and amount of exchangeable cations (CEC).