Chap. VI.] superficial deposits and soils. 129 



covered by licliens of various colours, and mthout any signs of water- 

 marks, which these turbid streams leave very distinctly. 



The dam-liko accumulations, as, for example, those of Combaly Pass 

 and at the mouth of the Taultooky ravine, may not improbably have been 

 formed by the torrents having been actually ponded back either by some 

 landslips or by some large masses of rock in course of transport being 

 brought to a stand-still by some impediment, or having reached a point 

 beyond which the pressure of the stream was insufficient to move them. 



The materials brought down subsequently would then be deposited 

 behind and above them, so that, under favorable circumstances, the stream 

 might be fairly dammed back till the weight of water behind the dam 

 sufficed to produce a debacle, or the water found some other outlet. In 

 a lake thus produced, a deposit of great thickness might soon be formed 

 by the joint action of the torrent and of the rain falling on the slopes 

 above the dam. Any cause subsequently arising to breach the dam would 

 immediately set up a current, which would cut deeply into the deposit 

 formed behind the dam, and these currents, aided by heavy rain-fall, 

 would tend to form tlie strange mounds above described. 



Sufficient evidence was not obtained in any case to be able directly 

 to attribute these phenomena to the cause above supposed, or to any other ; 

 but the above seems the most likely. No traces of any fossil whatever 

 were met with in any of these deposits, except in that north of the Sur- 

 ragoomuUay, on the banks of the Adagaripully nullah above described. 

 The soil of these valley accumulations is a red loamy sand, generally 

 -rather less ferinigiuous than the ordinary red soil of the low country, and 

 not remarkable for its fertility. 



The admixture of kunkur already referred to is occasionally so great 

 as to solidify the whole and form a peculiar deposit, which has already 

 been described when treating specially of that form of limestone. Of 

 the very sandy reddish soil covering the country where the granitoid 

 gneiss rocks occur, nothing more need be said than that it would appear 

 R ( 351 ) 



