Inverted Channels in the Eastern Sahara—Distribution, Formation, and Interpretation to Enable Reconstruction of Paleodrainage Networks

During the Cenozoic Era, the Egyptian Sahara was the site of fluvial activity in a succession of at least three main drainage systems, including the Gilf System (40–16 Ma ago), the Qena System (24–6 Ma ago), and the Nile (30 Ma ago to present). These systems developed as a response to wet conditions, the dramatic events of tectonic activity in the Red Sea Region and southwestern Egypt, and changes of sea level in the Tethys Sea in Late Eocene time to sea-level rise in Late Pleistocene time. The modern Nile consists of captured components of ancestral Nile segments. Representatives of those Nile ancestors and lost tributaries of the Nile have been buried beneath dune fields and sand seas, or have been eroded by wind deflation to be topographically inverted. In this chapter, we present the distribution of inverted river channels in the Egyptian Sahara, and a description of the mechanisms that led to the development of those features during several periods of time within the Cenozoic Era. Moreover, we offer some stratigraphic and geomorphic interpretations that enable reconstructions paleodrainage networks and paleoclimates during those periods of time. Further study of the geochronology and paleohydrology of these relics is necessary to reconstruct the fluvial and paleoclimatic history of the eastern Sahara.