182 B. Bj. Branfill — Fhysio graphical Notes on Tanjore, Sfc. [No. 4, 



the river mouths, because the sand is then moist from the recent autumnal 

 rains, the heaviest rain of the year, and therefore unmoved. But the south- 

 ward set of the rollers and beat of the surf must tend to drift the shore- 

 sand loosened by its violence, southward across the river mouths, which it 

 shoals, helping to form the bar of sand-banks and islands usually formed 

 in such situations. 



In January and February the north-east monsoon (wind) gradually 

 changes into land and sea breezes, which increase as the spring advances 

 with clear weather and a hotter sun. The sand of the sea-shore rapidly 

 dries and is drifted by the sea-breezes to the top of its slope, as long as 

 there is loose sand to drift and nothing to shelter it. 



The sea-breezes veer gradually to the south-east and southward until 

 in May they become strong ' long-shore* winds from the south, directly 

 transporting northward much of the blown sand collected along the coast- 

 ridge, in clouds of dust which settles in the hollows and tends to fill up and 

 choke the southern edges of the river out-falls and so to shift them north- 

 wards. 



With the change of wind from the north-east in January to south-east 

 and south in April and May, the ' long-shore' current changes from south 

 to north, latterly running rapidly northwards and bringing in the heavy 

 sea-rollers obliquely to the coast from the south-east, to dash in lines of 

 roaring surf on the shore, washing the sand of the beach northwards at 

 every stroke. This double action it is (perhaps chiefly) that drives the river 

 mouths northwards. 



Whether this is the right explanation or not, the fact remains that the 

 mouths of the rivers of the Coromandel Coast are continually shifting 

 northwards. 



This is seen best in the Mahanadi and Kaveri ; also in the Penner 

 (Pinaka), Nagari river, Kordaliyar, Kii-am, Palar and Vaigai. 



It is less noticeable in the Godaveri, Vellar, and Tamraparani. The 

 Kistna seems to contradict this tendency, and the Godaveri also has one 

 outlet apparently to the south of its delta, but these apparent exceptions 

 probably admit of some explanation. On the west coast, the Netravati 

 exhibits a similar tendency to make its outlet into the sea considerably 

 north of the spot it seems to be going to, as it approaches the coast. 

 The northward shifting of the Netravati mouth is probably due to the 

 northward set of the current, and the violent beat of the breakers during 

 the south-west monsoon, which has nothing to counter-balance it. It 

 seems probable that where the beach is sandy, the same tendency of the 

 river-mouths to shift northwards may be observed in Ceylon. 



After shifting for an indefinite period to the north, during which it 

 seems probable that the bed of the river must be silting up, especially 



