Chap. TV. 2.] metamorpiiic rocks. 101 



could be arrived at. The fact that no actual vent was discoverable in the 



,, „ case of any of these spring's suo-^ests the possibility 



No fossils in magnesite. , "^ ^ f & »& i j 



of their having ceased to flow^ because all passages 

 to the surface were effectually choked by the accumulation of travertin, 

 while the spring was not propelled from below with sufficient force to 

 open itself a fresh channel. The great qiiantity of calcedony and jas- 

 per here, and at Mootoonaikenputty, may perhaps have been due to a 

 high degree of temperatm-e in the water of these springs. 



About half a mile south-east of the ^'^Travellers'' Bungalow^^ at 



Volcondapuram, on the Madras-Trichinopoly road, 

 Volcondapuram. 



the surface is covered with travertin over several 



acres of ground. Several veins of not very pure magnesite also occur in 

 the travertin. Chalcedonic incrustations are common, and fragments of 

 jasper very numerous among the scattered debris. The magnesite veins 

 and travertin occupy high ground ; to the north and west they disap- 

 pear, as the ground drops, while on east and south this formation is cov- 

 ered up by cotton-soils. 



About 2f miles to the south-west, a small vein of beautiful 



Serpentine of Ellum- jellowish apple-green serpentine occurs at the 



baloor hill. f^Q^ ^f ^j^g Ellumbaloor' hill ; it is seen only 



for a few feet in length in a pit from which laterite road metal has been 

 excavated. Indeed, fragments of this serpentine in the freshly-spread 

 road-metal first attracted the attention of Mr. Blanford before this part 

 of the district had been examined. The serpentine is of very small con- 

 sistency, and the mass much weathered spherically. Its length follows 

 the same direction as the strike of the adjoining gneissic strata, which is 

 east 15° north. There is probably no actual connection between this ser- 

 pentine and the magnesian travertin deposit at Volcondupuram. 



At a point about 5 miles due north of Volcondapuram and 3 

 miles north of village of PoUiam, another travertin formation occurs, 

 under circumstances nearly the same as those at Tripunguly, differing 



(323) 



