NEWTON: LOWER TERTIARY MOLLUSCA OF THE FAYUJI. o t 



Before proceeding further, however, it will be necessary to refer 

 briefly to the stratigraphical features of the district under consideration, 

 which have been so ably described by Mr. Beadnell. From his memoir 

 we gather that the Fayura is one of the great depressions of the 

 Libyan Desert, being of circular contour and comprising about 12,000 

 square kilometres; it lies some fifty miles south-west of Cairo and 

 immediately west of that part of the Nile Valley which is between 

 Kafr el Ayat and Feslin, The more southern and western portions 

 include Wadi Muela, Wadi llayan, and Gar el Gehannem ; the 

 northern boundary being a range of hills known as Jebel el Qatrani. 

 Mr. Beadnell divides the region into cultivated land, lake, and desert. 

 The main part of the ' cultivated land ' is in the eastern half of the 

 depression, where the villages mostly abound. Like the Nile Valley 

 itself, the soil here is of alluvial character, being nourished by 

 a complete system of irrigation which emanates from the Nile through 

 the mitural canal of Bahr Yusef and its many offshoots, and so 

 furnishing the area with an abundant water supply, many of the 

 streams ultimately draining into Birket el Qurun. This latter, 

 situated to the north-west of tlie cultivated land, forms the 'lake' 

 area of the province, being a large sheet of brackish water, with 

 a nearly east and west axis of 40 kilometres and a maximum breadth 

 of 10 kilometres; it forms the lowest part of the depression. This 

 lake, in Post-Tertiary and early historical times, must have been far 

 more extensive than now obtains, as lacustrine deposits can be traced 

 over wide areas of what is now desert country. It is supposed to 

 represent all that remains of the ancient Lake Moeris when its 

 waters, according to Mr. Beadnell, must have covered an area ten 

 times the size of that occupied by Biiket el Qurun at the present day. 



The ' desert ' country of the Fayum may be said to surround the 

 lake and cultivated lands. This is the region of greatest antiquity, 

 being formed of Lower Tertiary rocks belonging to the Middle and 

 Upper Eocene Series, which have yielded the vertebrate and invertebrate 

 fossils as well as large masses of silicified tree remains. It is in the 

 escarpment area between the northern shores of Birket el Qurun and 

 Jebel el Qatrani that the chief fossiliferous tract occurs. Speaking, 

 generally, the strata of the Fayum are of a purely sedimentary 

 character, consisting of limestones, marls, clays, sandstones, etc., 

 which vary greatly in hardness and durability, the beds being nearly 

 horizontal or with only a slight northerly dip. Igneous rocks are 

 sometimes present, but they are regarded as having originated, more 

 or less, from local lava-flows. The stratigraphical sequence is given 

 as ]\Iiddle Eocene, Upper Eocene, Oligocene, Pliocene, Post-Pliocene, 

 and Recent. Certain igneous rocks referred to as intercalated basalts 

 occur between the topmost Eocene and the Oligocene, which are 

 considered to represent an arbitrary demarcation separating those two 

 fi>rniations. Further divisions have been recognized in these strata. 

 The ^riddle Eocene or Lutetian of European nomenclature is divided 

 by Mr. Beadnell into four groups. The first or oldest, at the base, are 

 termed the Wadi Ratjan Series, containing marine shells and 

 NnmmnJifes Gizehensis, and which occur at AVadi Muela, AVadi Bayan, 



