94 



Geological Features 



[NO. 1, NEW SERIES, 



in syenitic granite, or greenstone, is prevalent, while to the south 

 of it mica, combined with quartz and felspar forming the common 

 or porphyritic granite, is equally prevalent. 



We have now arrived in our notices of the country at the eastern 

 part of the Trichinopoly District, which is traversed by that re- 

 markable bed of fossil-shells already referred to, sometimes called 

 the Ootatoor marble. In the tour mentioned above, this region 

 was visited, and I proceed now to state a few particulars in regard 

 to it. 



In the vicinity of Ootatoor, the syenitic granite containing gar- 

 nets is very abundant, it crops out and lies on the surface in flat 

 masses and huge blocks ; and rises into hills and mountains im- 

 bedding in some places the blue or oolitic quartz, fine specimens of 

 jade, crocidolite, and a black curiously crystalline carbonate of lime 

 and small pieces of iron. 



About half a mile east of the Travellers' bungalow, the granite 

 disappears from the surface, or remains only in small quantities 

 and scattered in disintegrating fragments. The prospect from this 

 place to the north, east and south is that of a great plain extend- 

 ing in vast wave like undulations as far as the eye can reach.. 



The soil is a dark loam containing magnesia and lime evidently 

 formed from the disintegration of the rock on or beneath its sur- 

 face. Small pieces of red irony crystalline limestone as also pieces 

 of the marble full of small white shells of the multilocular class 

 called the turrilite are found here. 



In the rolling surface of this plain, there is a fair opportunity, 

 considering the loose and earthy nature of the soil, for the denud- 

 ing effects of the water, hence we see many of those ridges worn 

 into banks and mound-like and deep ravines by the torrents. One 

 of these, about a mile east of the bungalow is well marked. The 

 ravine is about 58 feet deep and lays bare the surrounding strata 

 to a considerable extent. The upper stratum on the western side 

 is a marl or earthy limestone and occupies a large portion of the 

 surface ; the next stratum below appeared to be an iron sandstone, 

 slightly resembling laterite yet regularly stratified, and of a red- 

 dish brown color, evidently containing a considerable quantity of 



