NILGHIEI HILLS. 



243 



slowly cut its course, aud the remains of which exist in the terminal 

 spurs and rocky ridges already alluded to. An instance in which this 

 is especially obvious is on the great feeder of the Pykara, which rises 

 on the Eastern flank of Tukulhullybetta.* (See Fig 7.) 



Fig. r//.— AUuvial plain on a feeder of the Pykara River near Tukullinllybetta. 



On the Mailur road, about 7 miles from Ootakamund, another very 

 good instance is seen, and the gorge which closes the alluvial plain, and 

 down which the Mailur road passes, is very fine and rocky. 



From the above descriptions, it is evident that at some period in the 

 geological history of the hills, there were several 

 lakes of a serpentine form occupying what are 

 now drainage valleys, but which were then closed by a ridge of hard 

 rock since cut through. Now it is evident that any obstacle closing 

 a valley excavated by running water must be of subsequent date 



* It is proposed by Mr. Fraser to take advantage of these natural bunds, and by filling 

 up with an artificial bund the gap formed in them by the stream, to reconvert the uj)per 

 part of the valley into a lake or reseiYoir, such as was undoubtedly its original condition. 



Ancient lakes. 



