20 rooTE : geology of madura and tinnevelly districts. 



chooly). It is well exposed in the quarries close to Shoilputty, where 



the rock is of a fine-grained dense variety of mauvey-pink colour, showing 



the bedding" only where freshly broken. The rock is also well seen at 



Moonooroopoo rock (where it is of a dull reddish-brown colour), and at 



the Paraikulara rocks west of the Tirushulai tank. At the latter place 



the rock which is slisrhtly hornbleudic is well bedded, the laminae being 



of rich pink and grey colours. The dip of the rock is westward in all 



these three outcrops. 



About 5 miles west of Tirushulai in and north of the village of 



Palaiyampatti (Paulayemputty) is a considerable 

 Aruppukotai beds. 



show of rich red granite gneiss beds which would 



appear from their mineral similarity to be extensions of a very similar 

 rock which forms the small rocky hill west of Aruppukotai (Arpoocotay) 

 2 miles to the south-south-west. This red rock is very largely quarried 

 and yields a remarkably handsome stone which is in great repute in that 

 region. Here also the beds have more or less easterly dip. 



North-westward of this band of granite gneiss and separated from 

 it by an intervening spread of cotton soil from 3 to 5 miles across is 

 a tract of strongly l)anded gneiss intermediate in texture between 

 granite gneiss and typical schistose gneiss which is particularly well 

 seen at and to the south-west of Mallakanur (Mullakenur) 5 miles east- 

 by-north of Virndupatti. Micaceous beds predominate here as generally 

 throughout tlie Madura and Tinnevelly gneiss region, but hornbleudic 

 Serpentinous rock at ^^^^ are also met with, while near Kovilpatti 

 Kovilpatti. (Covilputty) a mile to the eastward a bed of 



decomposed serpentinous rock was observed. Unfortunately this ser- 

 pentinous bed is exposed only in an inaccessible section in the side of 

 a well and could not be examined closely. About 4 miles south-west of 

 Makallanur and a little south of the village of Palavanattam (Kylassa- 

 pooram of map) a large quantity of debris of a very coarse-grained 

 greyish-white crystalline limestone is to be seen scattered over the sur- 

 face and rolled in the bed of a small water-coui'se. I was unsuccessful 

 in tracing the outcrop from which this limestone debris was derived. 

 ( 20 ) 



