61< GEOLOGY OF TIMCIIINOPOLY, &C. [CjIAP. IV. 1. 



occur about half way up through the series, and have been traced from a 

 little north of Thathensarapetta (Thatheng-arpaittai of map), westward to 

 the most northerly ridge, outlying from the Tullamullay and all along 

 that ridge. Westward thence they form two well marked wall-like ridges, 

 which disappear a short way east of the alluvium of the Karavetaur to 

 re-appear on the west side, and finally range beyond the limits of the map 

 to the south of Keerumboor, 6 miles west-south-west from Namkul. The 

 apex of the curve is, as before mentioned, not included within Sheet 79, 

 but there can be no doubt that the beds corresponding with them are 

 those appearing at Vellakaputty, and running thence with a southerly dip 

 to the north-east by east. They appear in force just west of the Salem 

 and Trichinopoly road, and again about a mile to the east. At a distance 

 of about 4 miles from the road, the bed ascends a conspicuous ridge, and 

 keeps along the crest of it for several miles, till cut olF by a great trap- 

 dyke, and apparently faulted with a great dislocation to the north. The 

 shift appears to amount to nearly 3 miles, but it would be hardly 

 possible to judge fairly of the extent . of the shift without renewed 

 and very careful examination ; the ground intervening between the two 

 portions of the iron bed being covered by a great flat of paddy cultiva- 

 tion and a large tank, which efiectually conceal the rocks at the most 

 important spot. The eastern extremity of the dislocated portion runs 

 up the most north-westerly spur of the Kolymullays, and is finally lost 

 sight of in the jungle covering the flanks of the great northern spur of 



the Kolymullays. Within this great curve is 



Inner series of beds. ,i- j^ j^ . o -i i i-i i 



another important set oi beds, which appear, how- 

 ever, only for a comparatively short distance, in the southern area of the 

 curves ; on the north side, on the contrary, they are largely developed. To 

 the south of Namkul they appear on the eastern and northern flanks of the 

 Kunnavaputty Hill,^ thence they may be traced in the direction of Keer- 

 umboor, to the south of which place they pass beyond the limits of the 



* This hill is not named in the map, tliougli indicated as a Trigonometrical-station. 



( 286 ) 



