L.—_Gravel Terraces:? Upper Pliocene._—Well marked terraces of gravel up to 170-180 metres above sea-level. East of Sêla. Character of deposit. East of Sersena and Roda. N.N.E. of Tamia, N.N.E. of Garat el Faras, east and north-east of Garat el Gindi. Relation to different series. Character of gravels at Elwat Hialla. West of Elwat Hialla gravel terraces almost completely removed by denudation. Traces near Widan el Faras and near Garat el Esh. Height of terraces in latter locality determined as 170 metres above sea-level. Terrace marks shore line of great sheet of water, whether freshwater or marine. The great plains of the Fayûm possibly in part plains of marine denudation 73 M.—_Gypseous Deposits: probably dating from the close of the Pliocene._—Extension in Nile Valley and Fayûm. Section at Medum. On the east side of the Fayûm. Gypsum cemented conglomerate. Close connection with upper part of gravel terraces 77 N.—_Summary of Pliocene Period_ 78 SECTION XIII.—PLEISTOCENE— Earliest existence of a freshwater lake. Probably not a remnant of the Pliocene sea or lake in which gravel terraces were formed. Intermediate denudation of area. Date of earliest entry of Nile waters doubtful. Freshwater lake of Nile Valley. Drainage down the Nile Valley and establishment of river. Breaking down of gravel ridge separating the valley and the Fayûm. Entrance of flood waters. Formation of lake and deposition of sediment. Subsequent disconnection of Nile Valley and Fayûm owing to erosion of river bed. Rise of Nile in prehistoric and historic times. Reconnection. Geological evidence for the existence of great freshwater Pleistocene lake. Position and dimensions. Fossil fauna of the lake, and its difference from all other Egyptian faunas. Blanckenhorn’s conclusions 79 SECTION XIV.—RECENT 81 O.—_Prehistoric._—Abundance of worked flints. Shores of lake inhabited by Neolithic and probably prehistoric man. Tamarisk remains. Probable age of flints anterior to Egyptian historic period 82 P.—_Historic._—Relations of the Nile Valley river system and the Fayûm. Lake Moeris a regulator of the Nile floods. Brought under control in XIIth dynasty. Early references to Lake Moeris. Its position disputed in modern times. Linant de Bellefonds’ assertion disproved by Sir Hanbury Brown. Archæological evidence for the site. Present day fauna of the Birket el Qurûn. Modern deposits. Blown sand. Erosion 82 APPENDICES 87