Note 36 — 9. Can Travel in the Great Tracts of the Libyan Desert which are now Waterless be facilitated by the Sinking of New Wells?

Though we passed within 10 kilometres to the east of Kissu on the return journey from Merga to Owenat in 1925, I could not observe the structure of the mountain very clearly, owing to haze. But it appeared to me to be a huge granitic intrusion rising through the gneiss which covers a large area hereabouts. The sandstone over which we had been travelling since leaving Merga gave place to gneiss about 40 kilometres before we came abreast of Kissu, and gneiss continued to be the country rock until we came within 30 kilometres of Gebel Owenat, when sandstone reappeared, at first capping low hills and then forming the plain.