114< GEOLOGY OP TRICIIlXOPOLYj &C. [ChAP. V. 



Can very,, in a band stretching' from the neighbourhood of Erungaloor, 

 G-nit of C u er about 10 miles north-north-east of Trichinopoly, as 

 '^"•^^^^y- far west as Caroorj and in all probability beyond 



that point. This band is from 4 to 6 miles wide, measuring from the 

 edge of the alluvium northwards, and is made up of reefs of granite 

 which run generally in a north-east by north direction. The rock appears 

 to have been intruded between the planes of bedding of the gneiss. It is, 

 as a rule, largely crystallized with but little mica, and contains very large 

 felspar (Orthoclase) crystals of a rich salmon colour. 



A very common form of granite throughout the Trichinopoly dis- 

 trict is a binary variety, consistmg of felspar and 

 quartz, in which the felspar is usually of a white 

 or yellowish- white colour ; though typical granite (quartz, felspar, and 

 mica) is of frequent occvu'rence. About 7 or 8 miles south-south-east 

 of Trichinopoly there is a very fine vein of this last in the bed of a 

 stream near Poodoor, in which the crystals of felspar are very large, 

 some of 4 or 5 inches in diameter, and in which the mica occurs in long 

 flat prisms of 3^ inches in length. This vein, like another of identical 

 character at Naivailie, a few yards south of the crystalline limestone, 

 shows two structures ; the sides of the vein are irregularly crys- 

 tallized, while internally it assumes the structure of graphic gi-anite. 

 West of the road from Encongoor to Trichapoor (Koolitullay Taluq) is 

 a large vein of binary granite in which quartz greatly predominates, but 

 the crystals of felspar, when they occur, are of immense size, some- 

 times as large as 3 by 2^ feet and more. Felspar crystals of yet 

 larger size occur in a granite vein at Colingaputty (in Kameul Talook, 

 Salem district) associated with plates of talc. In a granite vein of 

 largely crystallized structure between the Maguesian travertine deposits 

 (page 99) at Tripunguly and Trevellary Pagoda, we found a very beauti- 

 ful variety of felspar of a rich leek green colour. Some blocks of granite 

 from neighbouring veins, in which the felspar is of a deep salmon red 

 ( 330 ) 



