80 POOTE : GEOLOGY OP MADURA AND TINNEVELLY DISTRICTS. 



questions for the answering of which the data have to be collected by care- 

 ful and often long continued observations. So far as my observations 

 went, I came to the conclusion that nowhere is the sea making any serious 



encroachments, and that the advance of the land 

 Marine erosion small. 



by silting up of shallower parts of the coast has 



been much greater than the recession by general wear and tear of the 



coast. A very manifest advance of the alluvium of the Tambraparni 



delta has taken place during many centuries, as will be shown presently, 



and the increasing shoalness of Tutikorin harbour shows clearly that 



the silting up process is still continuing. 



It is a well known fact that the coasts of the Indian peninsula are 

 Action of the p-eat s^ept by great marine currents running up or 

 monsoon coast currents. ^^^^ ^j^g ^^^^^ accordingly to the prevailing mon- 

 soon, whether it blow from the north-east or south-west. These currents 

 flow with pretty equal force, but owing to the longer duration of the 

 south-west monsoon, it produces the greater effects, and all the rivers 

 flowing into the Bay of Bengal have a tendency to extend their deltas 

 in a north-easterly direction. This tendency, it will be seen, is mani- 

 fested in the case of the Tambraparni as well as in that of the Vaigai, 

 . Cauvery, Vellar, and other more northerly rivers. 



The historical proofs of the sea- ward advance of the Tambraparni 



Advance of the Tarn- delta have been worked out with great research 



braparni delta. ^^^ learning by Dr. Caldwell, Missionary Bishop 



in Tinnevelly district. The proofs of the advance of the delta 



obtained by the Bishop are the identification of the sites of two 



famous old seaports — the '' Kolkoi Emporium " 

 Sites of " Kolkoi " and 

 "Cailth" deturraiued by of the author of the Periplus Mare Erythreum 

 Bishop Ciddwell. i , /^ •, « 



and of the geographer Ptolemy, and the " Can 



of Marco Polo, the famous Venetian traveller. The " Kolkoi " 

 of the Greeks Bishop Caldwell identifies with Korkai, a place now 

 nearly 5 miles inland, which was the capital of the Pandyan kingdom 

 as early as the year 600 B.C. The tradition of its former great- 

 ness as the capital and as the centre of the pearl trade was found by 

 ( 80 ) 



