24 MARINE BIOLOGY OF THE SUDANESE RED SEA. 
Further north is another prominent point, Ras Benas, which shelters a: 
large bay and has a large island to the south, exactly in the same way as 
Ras Rawaya. So like, indeed, are the appearances of the two points that 
the same name, Makawa *, has been given to the islands in both cases. 
The Jezira Ridge on Ras Benas corresponds to the high ground on 
Rawaya, and the Makawa of latitude 23° 50’ N. is obviously the continuation 
of this range. Similarly the southern continuation of the range is repre- 
sented by the ‘“ Horseshoe Reefs,’ which still retains a fragment of the 
ancient island in the form of “a white rock” which “looks like a boat,” 
below which this range ends in another set of reets. 
The third prominent point of this coast isat the mouth of the Straits of Jubal 
(leading into the Gulf of Suez), where the Zét Hills run southwards into 
the sea, where they are broken into a chain of islands ending in that of Shad- 
wan. The process of denudation has here made comparatively little progress. 
Few reefs exist except those fringing islands—and the islands are high on 
all their areas, e.g. Shadwan 990 feet, Jubal 410. But imagine denudation 
to have progressed to a far greater extent and to have cut down the smaller 
islands to sea-level, their foundations being at the same time preserved or 
added to by the growth of coral, and we see that the conversion of a range of 
hills to a peninsula, island, and chain of barrier-reefs becomes complete, as in 
the case of Rawaya, Makawa, and Tiflah. The repetiticn of this arrangement 
on this coast is striking, but just as some ranges are entirely inland (e. g. the 
Abu Hamama range), so others are completely transformed to barrier-reefs, 
or perhaps were never elevated so high as to be continuous with the land, or 
even to project above the sea. or instance, the long reef, Shab Suadi, 
seems to be a continuation of the promontory of Salaka, but there are no hills in 
the vicinity that could be part of its range. The Barrier system inside Foul 
Bay, south of Ras Benas, is not connected with that point or its “ Jezira ridge.” 
To the south this reef system bears the Mirear (lat. 24° 40') and Siyal 
(lat. 23°) Islands and some small rocks, the islands being low and flat, only 
6 to 12 feet above sea-level, and composed of elevated coral. 
¢ 
THe KoRMATION OF CORAL-RaAG. 
An instructive comparison can be made between the elevated coral of the 
Red Sea coast and that of Zanzibar. Both are low, and contain fossilized 
specimens of the species now living in the adjacent sea, and are consequently 
among the latest of geological formations. In both cases the alteration of | 
the relative level of land and water has been effected in so regular a manner 
that the corals of the land retain relatively the position in which they grew 
when submerged. But in spite of these fundamental resemblances the physical 
properties of the rocks are as widely different as possible. 
* This Arabic name, meaning “that which is resistant,” has therefore a deeper significance 
than its donors supposed. 
