28 GEOLOGY OF TRICHINOl'OLY, &C. [ChAP. II. 



about 900 yards in leng-th). No shells were found which might give a 

 clue as to whether these sand accumulations are of marine or fresh-water 

 origin, but the fact of its being a " sharp sand^' favors the view of its 

 fluviatile origin. If of marine origin, they must have advanced a long 

 way inland from the coast, from which they are now 8 miles distance ; if, 

 on the contrary, these sand hills owe their origin to fresh-water, there 

 is no difficulty in ascribing their formation to a change in the bed of 

 the Coleroon, which would then appear to have shifted its course a couple 

 of miles in a northerly direction. 



2ndly. — From Koliar, a village 3| miles north of Tirmelwassel 

 (Trimelliwassel) , a spur of blown sand branches off in a south-west 

 direction, and extends (vsdth one break) to the north side of the inlet. 

 Tirmelwassel itself stands on a broad spread of blown sand. 

 Src'Qy. — A small patch north-west of Tranquebar. 

 4thly. — A ridge unconnected with the beach ridge, which runs from 

 about 3 miles north of Carricall (Karikal) down to the north bank 

 of the river. 



5thly. — Between Karikal and Nagore are two smaller detached 

 ridges. 



6thly. — Southward of Negapatam, the blown sand runs about a 

 mile inland from the beach, forming parallel and connected ridges. 

 The height of the sand ridges varies from 5 to 20 feet, rarely 

 exceeding the latter elevation. Tlie greatest ele- 

 vation is attained by an isolated sand-hill, on 

 which is built the Coopum, or fishing village of Negapatam. The 

 sand-hill in this case is fully 50 feet above the surrounding beach, 

 and commands a fine view over the level country all round. 



No general indications of a tendency to advance inland were ob- 

 served. This comparatively stationary condition 

 Movement of sand-hiUs, t i -n 



01 the bloAvn sand-hms appears to be caused by 



(250) 



