of the central bcown limestone which, superficially at least, is not very different from 

 the brown crystalline limestone. Lastly the Jebel Dukhan consists of a base of chalky 

 zone beds, above which are the Alveolina — Shark's tooth series, and the brown crys- 

 talline limestone, this last capped by a bed of resistant chert. 



Both the flanks and the saucer are conveniently subdivided again, the former into 

 four parts, north, south, east and west, and the latter into two, north-west and south- 

 east. 



These various natural areas are shown in figure 4. 



Figure 4. 

 Sketch map showing the natural areas of Bahrain Island, as follows:- 



Peripheral Zone. Northern peripheral area (black). Western and southern area (^ite) 

 Central Dome. Flanks, divided into north, south, west and east (spotted). Saucer, divided 

 into north-west and south-east (diagonal lines). Central plateau (horizon- 

 tal lines). Jebel Dukhan (cross hatched). 



51 



