The eminent geologists to whom this study of one of the most perplexing problems of Nile Valley structure is due have made an extremely significant contribution. Rising and falling lake levels within the Faiyum during relatively recent times, dynastic or at most Neolithic, have heretofore monopolized attention. The present writers have instead traced the geologic history of that region back beyond the origin of the Faiyum depression itself. The Nile Valley as a whole has been investigated as a background for this detailed study, and will itself be treated more at length in a later volume (see OIP 17, ed.). [From The New Past ,1931, p. 24].