J. MILNE ON THE SINA1TIC PENINSULA AND N.W. ARABIA. 



from the foot of which they spring ; but at several points a white 

 rock can be seen cropping out, showing this detrital matter to be 

 only a covering. This rock is a pure soft limestone of coarse 

 texture, on the surface of nearly every square foot of which the 

 section of a coral can be seen ; but these, along with other fossils 

 collected, remain yet to be described. 



The only one of these mounds which I had an opportunity of ex- 

 amining was about 90 feet in height, and showed an exposure of 

 about 30 feet of this limestone, as measured from its base, which is 

 about 10 feet above sea-level. From this it would appear that there 

 must have been an elevation of at least 40 feet. 



From this place up to Akaba there are many of these old reefs, 

 indicated by the numerous white patches which protrude through 

 the heaps of dark-coloured debris from the granite mountains, 

 most of which are at much higher elevations than the one just 

 referred to, some being especially visible on the flat plain near 

 Omaider. 



In confirmation of these indications of an elevation I may add 

 that Captain Evans, a Commodore of the P. & 0. Co's fleet, stated 

 to me that in the Gulf of Suez there are reefs which twenty years ago 

 could with impunity have been sailed over, but have now to be 

 avoided, the two most remarkable of these being : — one at the en- 

 trance to the Gulf of Suez, where the soundings which were at one 

 time 7 and 7| fathoms, are now only 3 and 3| fathoms ; and the 

 other at the head of the Gulf, called the Newport shoal, where there is 

 a like decrease in depth. 



I am told that indications of a shallowing of the water in these 

 seas may be seen by comparing an old chart with one of recent 

 construction ; the origin of it, apparently, can only be accounted 

 for in one of two ways — by an elevation of the sea-bottom, or a piling- 

 up of drifted materials by currents. 



As an additional proof of this rising of the land, I may quote 

 from Dr. Beke the official report of the British Consul at Jeddah, on 

 the Arabian Coast, who says " the sea on that coast is gradually 

 receding, owing to the formation of coral reefs," the geological 

 interpretation of which is evidently that the coast-line is being 

 elevated. 



That such elevations and perhaps oscillations should take place 

 is not unnatural, considering the wonderfully volcanic nature of the 

 adjoining peninsula of Arabia, examples of which may be seen in 

 the Trachonitis of Wetzstein or the Hauran of Burton and Drake in 

 the north, and the many traces of varied volcanic phenomena from 

 the shores of the Persian Gulf in the east to Jemen in the south- 

 west. In addition to these already known localities, it may be stated, 

 on the authority of Jakut, the Arabian geographer of the thirteenth 

 century, that many, although once chronicled, now remain to be 

 rediscovered. No less than 28 harras, or volcanic districts, are 

 described and their position identified by him, all of which are to 

 be found in the highlands and interior of the peninsula. The list 

 of these is as follows : — 



