been followed out to the uttermost fibril.

Reaching the crateriform summit, we found that the head of the
cone had either "caved in," or had been carried off bodily to be
worked. Here traces of fire, seen on the rock, suggested that it
had been split by cold affusion. A view from the summit of this
burrowed mound gave us at once the measure of the past work and a
most encouraging prospect for the future. We determined that the
Marwah or "quartz-hill" of Umm el-Karayat was the focus and
centre of the southern mining region, even as the northern
culminates in the Jebel el-Abyaz. Further experience rejected the
theory, and showed us half a dozen foci and centres in this true
quartz-region. The main hill projects a small southern spur, also
bearing traces of the miner. The block of green trap to the
south-west has a capping and a vein-network of quartz: here also
the surface is artificially pitted. Moreover, there are detached
white-yellow pitons to the north-east, the east, and the south;
whilst a promising hillock, bearing nearly due north, adjoins the
great outcrop. All have rounded conical summits and smooth sides,
proving that they are yet virgin; and here, perhaps, I should
prefer to begin work.

At our feet, and in north lat. 26 13', lies the settlement, in a
short gravelly reach disposed north-west to south-east; and the
bed is enclosed by a rim of trap and quartz hills. The ruins lie
upon a fork where two gorges, running to the east and the
north-east, both fall into the broad Wady el-Khaur, and the
latter feeds the great Wady el-Miyah, the "Fiumara of the
Waters," of which more presently. The remains on the upper
(eastern) branch-valley show where the rock was pulverized by the