1878.] B. Tt. BranSW— Phi^sio^raphical JVotes on Tmijore, ^c. 183 



near the outfall where the current is less, some unusually high flood may 

 be expected to top the bank and thus form a new outlet to the south. 

 This may possibly occur near the head of the delta, and the new channel 

 may take its course along the southern edge or border and recommence the 

 process of shifting its mouth northward again. This may be the explanation 

 of the Kistna apparently flowing along the southern border of its delta ; it 

 also points to a possibility of the Kaveri doing the same thing some day. 



When a river has opened a new mouth and abandoned the whole or a 

 portion of its course, especially that which ran parallel to the coast, it 

 seems only likely that a lagoon or haclc-ivater will be formed, which will 

 sooner or later silt up and eventually be reclaimed entirely from the sea. 



Having thus considered the causes of the northward shifting of the 

 river mouths on the Coromandel Coast, to which the Kaveri has been 

 subject continually during the formation of its delta, to the east of Triehi- 

 nopoly, the probable history of its more recent inland course offers itself 

 for consideration. 



Dr. Burnell of the Madras Civil Service states he has met with no 

 mention of the KoUadam (Coleroon), which is now the principal bed of 

 the lower Kaveri, by the early geographers, and thinks that the channel which 

 passes by Kumbakonam and Mayaveram and enters the sea at Kaveri- 

 pattanam, having retained the name of Kaveri throughout its course, was 

 the main channel of the river till the 10th or 12th century. 



From Ptolemy's map of the Coast of India, it would appear that 1,500 

 to 2,000 years ago, there was a spit of land jutting out into the sea at the 

 Kaveri mouth near " Ghaleris Emporium'' (Kaveri-pattanam), of which 

 there is now no trace, either above or below the sea-level contour line. 



Such a spit or shoal would, however, naturally disappear if the river 

 mouth shifted, or if any thing stopped the deposition of silt which formed 

 it, and this must have happened when the great irrigation works at the 

 head of the delta were constructed. 



At present the Kaveri-pattanam mouth of the Kaveri is nearly 

 silted up, and the principal outlet of the surplus flood- water is now by the 

 mouth of the Kolladam, where, according to recent maps, a new deltaic 

 projection and shoal are forming. 



The great irrigation works are supposed to have been constructed 

 in the 10th and 12th centuries, but local traditions represent them as early 

 as the year 200 A. D. In any case, the delta has been under irrigation from 

 time immemorial. The story of the Kaveri main channel would seem to be 

 somewhat thus : — After some long period of silting up from the deposit left 

 by the annual floods, the river in some unusual inundation must have over- 

 flowed its banks and found a new and easier course. 

 24. 



