INTEODUCTIO]Sr. vil 



stumps of trees of considerable size occur, indicating that in some parts, at least, in 

 the neighbourhood of the water the country was wooded. Later, within the historic 

 period (XII. Dynasty, beginning about 2778 B.C.*), the lake was converted into an 

 artificially-controlled reservoir, Lake Mceris, and was employed to regulate the supply 

 of water in years of exceptionally high or low Nile floods. At this date, though smaller 

 than the earlier Pleistocene lake, the water-covered area was far greater than at the 

 present time, indications of its former extent being found in old shore-lines, still 

 fringed with the stumps of tamarisk-bushes, and in the ruins of temples and cities 

 {e.g. Qasr-el-Sagba). These remains are now separated from the water by miles of 

 desert. Later still, probably in Ptolemaic times, the lake ceased to be used as a 

 reservoir, and the quantity of water admitted to the Fayum was limited, so far as 

 possible, to the amount actually required for the irrigation of the district. The 

 consequence of this was that the lake received only such surplus water as drained 

 from the cultivated lands, and its level began to fall until, within the last year or two, 

 it reached its smallest dimensions. Since then the more abundant supply of water 

 resulting from the vast irrigation-works in the Nile Valley has led to a considerable 

 area being reclaimed, and the consequent increase in the amount of water draining 

 into the lake has brought about a slight rise in its level. 



The cultivated land lies to the south and east of the lake, while on the north the 

 desert extends down almost to the water's edge, from which it is separated by a 

 belt of sand-dunes and swamp of varying width, covered with scanty vegetation, 

 consisting mainly of tamarisk and reeds. Along the whole of the north margin 

 also there is a band of lacustrine deposits widening out towards the east. These 

 beds overlap the edge of the Middle Eocene strata which form the lower parts of 

 the depression. 



With only one or two exceptions, the whole of the vertebrate remains described in 

 the present volume are derived from the Middle and Upper Eocene deposits lying 

 on the northern side of the lake, and it \Yill only be necessary here to give a brief 

 account of the geological structure of that region. Looking northwards from a 

 suitable point of view on the southern side of the lake, the northern slope of the 

 depression can be seen rising in a series of escarpments of varying height (see Map 

 and Section), and running roughly parallel to one another from about E.N.E. to 

 W.S.W. ; the terraces between the successive steps vary in width from mere ledges 

 to plains some kilometres wide. There are three main escarpments, of which the 



* Flinders Petrie, ' A Historyof Egypt,' vol. i. p. 147. 



52 



