256 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. 



character of the beds continues throughout the whole of this extended 

 line of 500 miles. 



But these outliers do not indicate the extreme western limit of the 

 gypsum-formation ; for I am convinced that, after forming a trough 

 under the alluvial basin of the Tigris and Euphrates, through which 

 it occasionally appears as islands in a shallow, the same series is con- 

 tinued into the deserts of the Aneiza Bedouins ; and it is probably 

 again represented in Syria. 



At Meshed Ali, the sacred shrine of the Sheah Mahomedans, the 

 banks of the Bahr-i-Nedjef and the cutting of a new canal expose a 

 section of about 50 feet through horizontal beds of — 



1. Very fine white quartz-gravel, imbedded in friable, reddish, 



calcareous marl ; 12 feet. 



2. Similar quartz-gravel, in friable calcareous earth ; 40 feet. 



Midway between Musseib on the Euphrates and Kerbella is a slight 

 rise in the surface of the ground, and which, from its whiteness, 

 attracts attention. It is a bed of loosely cemented fine gravel, resting 

 on amorphous gypsum, and contains crystals of selenite. The road 

 passes for half a mile over the south-eastern extremity of the bed, 

 which extends in a low undulation towards the N.W., and is lost on 

 the horizon. 



The components of this gravel are precisely similar to that at 

 Iskenderia Khan (alluded to below), between Baghdad and Baby- 

 lon, where gypsum again appears, and causes a remarkable ridge 

 on the otherwise level desert. It is first met with half a mile to the 

 north of the Khan, and runs in a general direction N.N.W. by S.S.E. 

 To the south of the Khan it is one mile broad. It sinks into the 

 alluvial plain on both sides, but reappears near Mizerakji Khan, on 

 the west about two miles, whence another ridge trends away to the 

 N.N.W. The gypsum protrudes in small masses, exhibiting no 

 regular stratification, but appears contorted and irregular ; in some 

 places it is hard, compact, and disposed almost in the form of septaria, 

 or with a resemblance to a tessellated pavement. In both varieties 

 small pebbles are observed, which do not, however, exceed a quarter 

 of an inch in diameter, if even so much. 



Mr. Ainsworth casually mentions the pebble-beds of Iskenderia ; 

 but he appears to have overlooked the gypseous deposit, which is 

 here quarried to the depth of 3 or 4 feet, burned, and conveyed to 

 Baghdad, where it is used in the internal decoration of houses. 



The pebbles associated with this gypsum deposit are : — 



1. White, reddish, yellowish, and milk-white quartz. 



2. Siliceous stone, of pinkish quartz with white grains of imbedded 



quartz (one specimen). 



3. Flint, with white and reddish- white coating. 



4. Hornstone, approaching agate. 



5. Semi-transparent agates (a few). 



6. Cherts of various colours, from grey to almost black. 



7. Light-green chert, approaching jade. 



I 



