'The Expedition for the survey of the rivers Euphrates and Tigris, carried on by order of the British government, in the years 1835, 1836, and 1837; preceded by geographical and historical notices of the regions situated between the rivers Nile and Indus. In four volumes. With fourteen maps and charts, and embellished with ninety-seven plates, besides numerous wood-cuts. Volume the first.' [‎563] (654/905)

CHAP. XXII.] PRINCIPAL CHAIN OF ARABIA. 563
eastward to the Gulf of Akabali, and towards Petra; also
northward along and beyond Wadi A seasonal or intermittent watercourse, or the valley in which it flows. Arabah, till they are lost
in the distance. Over all this scene most of the narrow wadis
being hidden, the spectator looks in vain for anything like a
plain or valley, or even the appearance of verdure.
St. Catherine, in the group of Sinai, is the culminating Branch from
point of the mountains of Arabia Petreea: from this a great Catherine,
branch runs in an east-south-easterly direction; and the
mountain system of Arabia, which strongly resembles that of
Iran, appears to have its root in this offset. The branch just
mentioned winds along the western side of the territory for a
distance of nearly 1400 miles, forming part of the lip of the
vast basin of the Red Sea; on the other side of this sea there
is a similar range, running parallel to, and at nearly an equal
distance, from the African shore. The former, as has just
been seen, is connected with the primitive formations of Asia
Minor; and, in striking south-eastward, it first skirts the Gulf
of Akabah with bare pinnacles of rugged trap or basalt, and
then inclines a little more towards the interior: its succes
sive groups are less or more connected together, and it makes
a sweep round Medina, sending towards that city different
offsets, such as Jebel Ohod, the scene of the most arduous of
Muhammed's battles, Jebel Ayra, situated on the opposite or
south-western side of the town ^ also Koba, El Kebleteyn,
with others, which are chiefly composed of red granite.
Onward the chain inclines towards the Red Sea, enclosing Mountains
a succession of rocky defiles and occasionally plains, some of Mekkah and
which, such as El Nazyr, 2 are of considerable extent; it after- Medma -
wards changes its direction, sweeping round the eastern side
of Mekkah under the name of Jeb-el-Kora, or Karrah; a bare
rugged mass of calcareous rock, mixed with black flints and
scattered masses of granite, and having the summits nearly
on the same general level. Such is the prevailing formation
as far as the former city; from whence, to the latter, por
phyry, granite, and limestone rocks are found in the highest
ridges, and calcareous masses in the lower. After passing
1 Burckhardt's Travels in Arabia, vol, II., p. 226-230.
8 Ibid., p. 132.
4 c 2