46 FOOTE : GEOLOGY OP MADURA AND TINNEVELLY DISTRICTS. 



7, the Sivaganga tract extending from the Upparu down to the Vaigai 



river ; 

 8j the Mudukan Kulam (Moodoocuncolum) tract which occupies the 

 slightly rising ground between the alluvium south o£ the Vaigai 

 river and that of the narrow valley of the Gundar ; 

 9, and lastly, the Parnalli tract between the Gundar and the coast 



alluvium on the north side of the Gulf of Manar. 

 To the south-westward of the Vaippar (Vypar) in Tinnevelly district 

 only faint traces of the lateritic beds occur, too ill-defined and scattered 

 over the surface of the older rocks to admit of their being mapped. 

 These will be referred to again a little further on. 



With regard to the Arrantangi tract (No. 1), there is nothing more to 

 be said than that it shows the typical conglo- 

 meratic form very well along the high-ground on 

 the left (east) bank of the Vellar to within about a mile of Arrantangi 

 fort. Further east it rapidly becomes more and more sandy, and finally so 

 strongly resembles the reddish sandy alluvium seen near the sea, that it is 

 extremely hard to say where the boundary between them should be drawn. 

 In the second, or Shenkarai tract (No. 2) the conglomerate is very 



thick and massive over an area of several square 

 Shenkarai tract. . . .... 



miles in extent and remarkably rich in iron, as is 



clearly indicated by the rich red colour of the wheel tracks passing over 

 the great bare sheets of rock which are a very characteristic feature of the 

 rock in that immediate neighbourhood. South of A3'^angudi a consi- 

 derable iron smelting industry seems to have existed at some not 

 very remote period, if one may judge by the size and condition of some 

 very large heaps of slags which are there to be seen. 



By far the greater part of the Shah Kotai tract (No. 3) is occupied 



by the hard laterite which is often more homo- 

 Shah Kotai tract. 



geneous than conglomeratic in texture and covers 



the surface of the Cuddalore sandstones in extensive and continuous sheets 



oF very dark reddish -brown (almost black) colour. These are specially 



well seen at Kilanelli Kotai (Keelanelli cottah), where the walls of the 



( 46 ) 



