20 



PHYSICAL GEOGEAPHY. 



[PART I. 



conglomerate, similar to that at Adam's Bridge and 

 Manaar. 



The phenomenon of the gradual upheaval of these 

 strata is sufficiently attested by the position in which 

 they appear, and their altitude above high-water mark ; 

 but, in close contiguity with them, an equally striking 

 evidence presents itself in the fact that, at various points 

 of the western coast, between the island of Manaar and 

 Karativoe, the natives, in addition to fishing for chank 

 shells 1 in the sea, dig them up in large quantities from 

 beneath the soil on the adjacent shores, in which they are 

 deeply imbedded. 2 



The sand, which covers a vast extent of the peninsula 

 of Jaffna, and in which the coco-nut and Palmyra-palm 

 grow freely, has been carried by the currents from the 

 coast of India, and either flung upon the northern beach 

 in the winter months, or driven into the lake during the 

 south-west monsoon, and thence washed on shore by the 

 ripple, and distributed by the wind. 



The arable soil of Jaffna is generally of a deep red 

 colour, from the admixture of iron, and, being largely 

 composed of lime from the comminuted coral, it is sus- 

 ceptible of the highest cultivation, and produces crops 

 of great luxuriance. This tillage is carried on exclusively 

 by irrigation from innumerable wells, into which the 

 water rises fresh through the madrepore and sand ; 

 there being no streams in the district, unless those perco- 

 lations can be so called which make their way under- 

 ground, and rise through the sands on the margin of the 

 sea at low water. 



Wells in the Coral Rock. These phenomena occur 

 at Jaffna, in consequence of the rocks being magnesian 

 limestone and coral, overlying a bed of sand, and in 



1 Turbinetta rapa, formerly known 

 as Valuta gravis, used by the people 

 of India to be sawn into bangles and 

 anklets. 



a In 1845 an antique iron anchor 

 was found under the soil at the north- 



western point of Jaffna, of such size 

 and weight as to show that it must 

 have belonged to a ship of much 

 greater tonnage than any which the 

 depth of water would permit to navi- 

 gate the channel at the present day. 



