GNEISSIC ROCKS. 



31 



gneiss are to be seen in the rocky hills at Valliyur (VuUioor) and Teka 

 Valliur (Theeka Vullioor) and at Kallikulam 

 a rai ou cr p . (Kullycolum) 4 miles to the east-south-east. The 



dip of the bedding in the Suttu Pottai appears to be southerly, and in 

 the Valliur hill a little to the south it appears to have changed and 

 become northerly. These dips agree well with the requirements of the 

 easterly extension of the great synclinal ellipse spoken of above (page 29). 

 Further south still the general dip of the rocks is northerly as it should 

 be to suit the ellipse theory. The predominant form of gneiss in 



Manpottai and Eruk- ^^^ south is a quartzo-felspatho-micaceous rock, 

 anturai liornblendic beds, i^^^^- ggyeral outcrops of hornbleudic gneiss were 

 also noticed, e.ff., the Manpottai (Great Trigonometrical Station) 

 4 miles south of Panagudi (Punnaugoody), and others at Erukanturai 

 (Irkunthoora) 7 miles to the south-east, and again at the north of 



ViziapattiHornblendic ^^^ Viziapatti (Vissiavethee) creek. One of the 

 granite gneiss. hornblendic beds at this place contains wollas- 



tonite, with coccolite and calcspar. The hornblendic gneiss here runs 

 out into the sea forming a small reef visible for some hundi-ed yards at 

 low water. At several other places the gneiss rocks jut out a little 

 distance into the sea, e.ff., at Kuttankuli (Kothaungculle) 2 miles to the 

 north-east, at Idindankarai (Iddingekurra) 1 mile to the south-west. 

 Bather more than a mile to the west of the latter place a narrow strip of 

 granite gneiss shows for about 3 miles along the coast. Its western end 

 is due south of the Kudankulam Trigonometrical Observatory which is 

 the southern extremity of the Cape Comorin base line. 



There appears to be no connection between these gneissic beds and 



,. , , the reefs which stretch along this coast, as the 



JNo connection between ^ 



gneiss ridges and exist- latter always run parallel with the coast line from 

 which extensions of the gneiss beds would diverge 

 very widely. These reefs are partly ridges of marine sandstone now 

 in course of formation, partly coral fringing reefs, and will be separately 

 treated of further on. 



A very remarkable feature in the gneissic region south of Trichinopoly 



( 31 ) 



