Capt. Grant on the Geology of Cuich. 321 



been broken^ and covered with fragments of rock, its present level outline may 

 be ascribed to subsequent operations. The Runn is bounded to the north, as 

 already stated, by the Thur or Little Desert, a district composed entirely of 

 sand. The Loonee and Bunass rivers also flow through a sandy soil, as do 

 many other streams which enter from the Cutch side. Now, during- the peri- 

 odical floods, vast quantities of sandy alluvium must have been brought down 

 by these rivers, deposited at their mouths, and washed thence and spread over 

 the surface of the Runn by the sea- water annually blown up at its eastern and 

 western extremities. This operation, repeated yearly, would fill up all inequa- 

 lities, and produce in time a level surface. It is probable, however, that the 

 present state of the district may also be, in some measure, owing to a gradual 

 rising of its bed, as it is only to such operations that some of its shores, as 

 those of the inlet above mentioned, can be ascribed. 



There are also many facts to prove, that this tract has been elevated at very 

 different periods. The high hills bordering its southern shore are, as before 

 stated, composed principally of the laminated series, and their surfaces are co- 

 vered with Ammonites, Nautilites, Belemnites, and other fossils of that geo- 

 logical period ; whereas along its immediate line of shore, there are generally 

 low ridges, composed of rocks fufl of marine remains of a totally different cha- 

 racter, many of them belonging to existing species. Numerous small rocky 

 islets, consisting of shells agglutinated into a solid mass, occur in various parts 

 of the Runn, and are barely raised above its present level. They are pro- 

 bably merely the higher portions of large tracts, the lower parts of which are 

 covered by sediment. 



Natural Walls on the Runn how formed. — Still more striking instances of 

 the effects of upheavement, since the Runn assumed its present characters, 

 are exhibited in the detached, elevated masses of rock which I have called the 

 Natural Walls on the Runn. 



They consist (see woodcuts) of disconnected portions of rock rising abruptly 

 from the surface of the Runn, and presenting a smooth, vertical wall, occa- 

 sionally upwards of thirty feet in height, and in one instance upwards of two 



End \ievv of a wall, about 15 feet high, and two miles long. 



miles in length. Some of them resemble domed or vaulted buildings, the 



