32 GEOLOGY OF TRTCinXOPOLYj &C. [ChaP. II. 



The mouth of the A^ellaur is little more than 4 miles from the 

 most northerly arm of the Coleroon^ which falls into a sort of lagoon 

 formed by some islands at the mouth of the main river.''^ 



Between the two rivers the blown sand scarcely forms a ridge, but 

 rather a flat expanse, with numerous isolated hillocks, amongst which at 

 Killay, opposite to Porto Novo, there are rather extensive salt-pans. 

 North of the Vellaur the blown sands occur in several high and ex- 

 tensive ridges, besides the coast ridge, which is of great breadth, and 

 extends up to Fort St. David. 



Soils of the Tellaur Alluvmm. — The remarks made on the soils of 

 the Cauvery delta and river flat apply equally well here, the black humic 

 earth and pale sandy soil both occurring, though the latter is proportion- 

 ately less developed than the former. 



Marine beds in the Alhiviiim. — That at no very ancient period 

 (geologically speaking) the sea washed the base of the promontory ter- 

 minating in the cliffs of Capper's Hill (at Cuddalore) , is incontestably 

 proved by the existence of beds abounding in fossil marine shells of 

 existing species at Kandyamallur, a village near the southern extremities 

 of the great Permalyeri tank. 



The quantity of shells here is so great that they are largely used for 

 the purpose of making a veiy fine quality of chunam (lime). These 

 beds seem to stretch away right to the coast in an easterly and north- 

 easterly direction, and in a southerly direction the fossil shells were 

 observed on the west side of Chugen villi tank, beside a group of Palmyra 

 palms. Many shells were collected where the high road crosses the 

 river by which the surplus water of the great tank is carried into the 

 Cuddalore back-water. 



* This creek abounds in mollusca, Crustacea, and fish- Muggers (Crocodili(s hijjorcafws, 

 Cuv.) wei'e also observed. 



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