AVIFAUNA OF CHOTA NAGPUR. 359 



invoked to account for all sorts of natural phenomena, are what ? 

 at first sight, might occur as satisfactory explanations. If even 

 the first be not an absolute physical impossibility, a little exa- 

 mination of the country shows that they are neither of them the 

 true explanation, while at the same time it reveals what has been 

 the modus operandi. Throwing the imagination back to the 

 distant period when the last flow of volcanic material or trap 

 spread over the sandstones which filled the Sirguja valleys to a 

 level Avith the Main Pat, the Pilka and other hills which now 

 furnish indices of the former thickness of the deposit, we can 

 conceive that a vast lake or lakes were formed in which the 

 singular laterite formation which now rests on the trap was in 

 all probability deposited. The rivers flowing from these lakes 

 had then a natural fall northwards, which enabled them to cut 

 down the hard ridges of metamorphic rocks from above. As 

 these cuttings progressed, lateral streams were busily at work in 

 the softer sandstones, cutting them up and carrying the mate- 

 rials to the main streams ; so reducing and rescooping the 

 valleys to their original form, but leaving here and there a 

 patch of sandstone sufficient to enable the geologist to read 

 and interpret the past history. 



The ridges of metamorphic rock, forming the barrier, once 

 more stand out in relief, as we must suppose them to have done 

 before the deposition of the sandstone ; but they are now cut 

 across by channels, which there is no reason for supposing 

 existed originally, or were formed in any other way than by those 

 agents which we see in operation at the present day. 



The next rain-basin, in an easterly direction, is one which 

 feeds the Mohur, the Mohanee and other rivers whose 

 waters find their w T ay to the Ganges through the plains of 

 Patna* 



On the north-east of the area lies the rain-basin of the 

 Damuda and of its principal tributary the Barakar. These 

 rivers take their rise in the highlands of Hazaribagh, in their; 

 course traversing that district and a portion of Manbhum. 



A few years ago a project was set on foot to store the head 

 waters of these rivers in some large enclosed valleys, with the 

 view of checking the inundations which occur from time to 

 time in the Burdwan district, and keeping up a constant supply 

 of water for a canal which was to connect Ranigunj with the 

 Hugli. Having seen much of that part of the country 1 am 

 inclined to express a doubt as to the success of either branch of 

 this project, at least with reservoirs of only the proposed number 

 and dimensions. 



