28 



in both cases is about 220 miles inland from tbe present coast line, 

 and it is estimated that the area of delta land at this part is 

 60,000 square miles with a depth of 400 feet of sand, alluvial 

 clay, and pebbles. 



In the year 1840 a boring was taken at Fort William, 

 Calcutta, which shewed the strata to be sand, alluvial clay, sand 

 with water- worn pebbles down to 480 feet. At a depth of 392 feet 

 a few pieces of river washed coal were brought up. 



On the "Western coast of the peninsula deltaic rivers are not 

 met with, the rivers being so insignificant in length and volume 

 as compared with those on the eastern coast ; the feature of that 

 coast is the formation of lagoons divided from the sea by a narrow 

 strip of sand ; the sea is stronger than the rivers and bars the 

 mouths causing the rivers to back up over the flat ground and 

 form large lakes which take the ordinary discharge of the rivers 

 and only in heavy rainy season does the level rise to a height 

 sufficient to burst the bars. Some of these are 1 8 miles in length 

 and some are 10 miles broad, the depth varying from 2 or 3 feet 

 to 14 or 15. Connected as they are by canals they form a splendid 

 line of inland water communication. 



The silt brought down in the fresher and floods caused by the 

 heavy rains, must necessarily be accompanied by a gradual 

 denundation of the Hills, from whence the rivers and streams 

 proceed, and there are many remarkable looking rocks or rocky 

 hills which bear evidence of having once been covered with soil 

 and vegetation which has been gradually washed away by the 

 rains ; the Trichinopoly rock is an example of a perfectly denuded 

 hill. 



The irresistible power of running water especially on rocks 

 that are in the least degree soluble is nowhere more clearly 

 demonstrated than at Jabalpur, where the river has cut through 

 the marble rocks to a great depth, an instance of the erosive 

 action of running water on calcareous rock. 



In conclusion, a few words may be said on evaporation, which 

 in the hotter parts of India is at the rate of ^ of an inch per day, 

 and necessarily is followed by a change in the hygrometric state 

 of the atmosphere, and the damp air rising from large areas of 

 irrigated fields is sufficient very often to so saturate the air above 

 that rain falls in districts where rain is scarce indeed. Notably is 

 this the case in Sind where the records show that since the 

 extension and resuscitation of irrigation in that rainless district, 

 the 5 inch and even the 10 inch rain contours are rapidly gaining 

 ground. And similarly in Egypt since the construction of the 

 Suez Canal the effect of the evaporation from that large area of 

 water known as the Eitter Lakes has been to give a rainfall to 

 Suez and Ismailia which was unknown to those places before 1870. 



