G^ GEOLOGY OF TRICIIINOPOLY^ &C. [ChAP. IV. 1. 



and the immense talus resulting in conscquencej renders it very difficult 

 to find a spot where it is practicable to measure the width of the out- 

 crop. The northern or Natamung-alum (Sircar Nauta) bed is near that 

 village of good quality, but not so rich as the main ridge bed, which seems 

 quite equal to the very richest parts of the finest beds of the Kunjamul- 

 lay and of the Tullamullay-Kolymullay series in the E-ajahpooram 

 (Ranzepoor) Talook. 



The highly magnetic nature of the rock renders it very difficult, in 

 many cases, to get a correct idea of the course of the beds if they are situated 

 in thick jungle, unless there be some very decided landmark by which, to 

 work, as the compass becomes utterly useless near the beds. Several of 

 tbe beds met with had to be laid down merely with, regard to the general 

 configuration of the country. This difficulty was experienced several 

 times in tracing the connection between the iron beds of the Valoor hill 

 and the Neighemullay, and the positions assigned on the map to the 

 intermediate parts can only be regarded as approximately true, the map 

 itself being deficient in that accuracy of detail in its topography which, 

 would enable the beds to be carefully laid down. The general direction 

 of the strata all over the area under report, namely, a trending from west- 

 east to south-south-west, north-north-east, is very well shown in the coiu'se 

 of these iron beds, running, as they do, from along the curves of the 

 Tainandamullay range. 



'incl. The Tullamullay-Kolymullay group of heels. — This group 

 TullamuUay-Kolymul- ^^^^^^s very conspicuously in a vast curve formed 

 lay series. jj^ ^j^g southern part of Salem district by a very 



large number of the strata constituting the gneissic system. It will be 

 seen, on referring to the map, that this great cm've is not altogether 

 included in the map, the western and apical part of the curve Ijdng 

 beyond the limits of our report, and not having, for that reason, been 

 followed up and mapped. There is no doubt of the existence of the curve 

 of the lowermost beds, and the curving of many of those overlying the 

 ( 284 ) 



