HILLS NOllTH OP ADEN. 27 



possibly be grauite; also hornblende rock with lines of foliation, 

 granular quartzite or quartzitic sandstone and white translucent vein (?) 

 quartz. Amongst the volcanic pebbles are those of basalt and of very 

 vesicular or scoriacous lava. The metamorphic pebbles are far more 

 plentiful than the volcanic, from which it might be inferred that the 

 latter come from a greater distance. By the same rule, however, the 

 limestone rocks would be the furthest off of all, as pebbles of such 

 are the rarest, while in reality they are the last beds through which 

 the river flows. This is worthy of note, for in the Wadi el Kebir, below 

 Lahej, metamorphic and volcanic pebbles are common, whilst there are 

 none of limestone or sandstone; but this fact does not prove that the 

 southern flanks of the hills, where the river debouches from them west 

 of Jibal Manif, are not of stratified rock. 



The pebbles in the Wadi el Kebir include foliated gneiss with 

 white felspar, quartz and black mica, a white non-foliated felspathic 

 rock, possibly granite, and difierent varieties of lava. 



It appears then that the Jibal Sliiap range of mountains to the 

 north and north-east of Aden, are composed of metamorphic and 

 volcanic rocks, with stratified rocks of mesozoic age on the southern 

 flanks, the latter having a southerly dip and very probably overlying 

 the metamorphic. 



Where I visited the most southerly outliers of the hills, the con- 

 ditions necessary for artesian borings are certainly not present ; whether 

 they be so further north, in the interior of the main range, I cannot 

 pretend to say ; but the point is not one of much practical importance 

 for the expense, the engineering difficulties, and the uncertainty, of 

 bringing water 40 or 50 miles, from an elevation of more than 1,000 feet 

 and through a desert constantly liable to the incursion of hostile tribes, 

 quite suffice to put the Jibal Shiap mountains out of the question in 

 any scheme for the water-supply of Aden. 



( 283 j 



