«i42 On the Geology of Cuich. [OcTc 



of violent movements, such as must have upheaved the Keera, 

 and its surface to have been broken, and covered with fragments 

 of rock, its present level outline may be ascribed to subsequent 

 operations. The Ruun is bounded to the north, as already stated, 

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

 The Loonee and Bunass rivers also flow through a s>ndy soil, as do 

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

 the periodical 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 inequalities, 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 covered with Ammonites, Nautilites, Belemnites, and 

 other fossils of that geological period ; whereas along its immediate line 

 of shore, there are generally low ridges, composed of rocks full of ma- 

 rine remains of a totally different character, many of them belonging to 

 existing species. Numerous small rocky islets, consisting of shells ag- 

 glutinated into a solid mass, occur in various parts of the Runn, and are 

 barely raised above its present level. They are probably 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 char- 

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

 have called the Natural Walls on the Runn. 



They consist of disconnected portions of rock rising abruptly from the 

 surface of the Runn, and presenting a smooth, vertical wall, occasionally 

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

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

 the reversed side consisting of a talus of broken fragments of rock and 

 soil. In one place these walls form a semicircle about 500 yards in dia- 

 meter, both walls sloping outwards. That the walls have been uplifted 

 into their present form is quite evident, first, from the stones being all 

 on end, that is, with the grain in the direction of their present position, 



