Appendix Il: Phytogeography and Geogoly. 1099 
the upper part of Wady Kene and the western plains have been 
proved to extend for over 200 kilometres from near the Galala hills 
in the north to the watershed near-Kene Qoseyr road on the south, 
though their breadth rarely exceeds 20 kilometres. Otherwise there 
are no important level areas in this region. The main Western 
Drainage of this area opens at one point only, viz. Kene itself. The 
_ highest ridges of the Red-Sea-Hills are near their eastern edge. 
The Red-Sea-Hills are not one continuous chain, but a series of 
ranges, advancing in echelon, each now longitudinal massif to the 
south being further east, though remaining parallel to its predecessor. 
The association of longitudinal and transverse rifts has given rise 
to mountain blocks. The Nubian sands and softer sandstones are 
the chief cause of many of the great plains and minor Valleys. 
Dykes have an important effect in the lower country bordering the 
Read-Sea-Hills, giving rise to a number of long parallel ridges with 
red crests or black outlines, while inversely, the softer diabases, by 
their rapid wearing away, are in many cases the cause of gullies. 
Red granite is one of the principal mountain-formers in the Red- 
Sea-Hills, rising in steep slopes from among the lower foot-hills, 
but in view of the complexity introduced by faulting, it is often 
difficult to say how far these masses are intrusions, which have 
withstood denudation better than the surrounding rocks. Its cha- 
racteristics are either very sharp precipitious peaks, or when more 
denuded, rounded outlines. 
In this district are only about 20 typical plants. The following 
list shows the principals of than: 
Zygophyllum coceineum var. Thalassia Hemprichii. 
berenicense. Cymodocea rotundata. 
Avicennia officinalis. »  serrulata. 
Statice axillaris. »,  isoetifolia. 
Atripiex farinosum. sa) -Clliata: 
Haplopeplis perfoliata. Diplanthera univervis. 
Halophila ovalis. Aeluropus brevifolius. 
»  stipulacea. 
