Lxxxvi Journal of the Asiatic Society of Beiiqal. [N.S., XII, 

 wards against the Indian table-land, and the rock surface of 



Northern 



downward 



tween the mountains and the table-land. This explanation is 

 not satisfactory : if the surface of Asia is being pushed south- 

 wards in wrinkles against the table-land, it is difficult to 

 understand how it is that a deep trough borders the table-land. 

 Why should the solid crust be bent downwards by a horizontal 

 pressure from the north : if the crust is being pushed against 

 this table-land, it should be heaped up all round it. 



The explanation of the Gangetic trough that is supplied 

 by the Flotation theory is this : the Earth's crust is likened to 

 a floating raft: the more weight you place upon a raft, the 

 deeper it sinks into water. The Ganges and Jumna and other 

 rivers are continually depositing fresh sediment upon these 

 plains, and the crust according to this theory continually sinks 

 downwards by the weight of the sediment. When we see the 

 massive rocks of Kaimur and Mirzapur supported easily by the 

 crust, it is difficult to believe that it cannot support a thin 

 layer of silt without yielding. 



You will see from this chart, that the Ganges and Indus 

 have filled up their trough with silt, but that the Tigris and 

 Euphrates are behindhand ; the Persian Gulf is an unfilled 

 trough which will be filled in time. 



Here is a chart of Japan, showing the Tuscarora deep, a 

 long submarine trough ; it is over 24,000 feet deep, and it is 

 continued to the north-east by further troughs lying in front of 

 the Kuriles and Aleutian Islands, and attaining depths of 

 28,000 feet. How then can it be argued that the Ganges 

 trough has been created by the weight of its own silt, when we 

 see that the Euphrates trough and the Japanese trough are un- 

 filled. These troughs exist before the silt comes to them. 

 The idea that the wmorht of silt causes subsidence arose, I 



:hat the places 



posited are frequently found to be subsiding. But the truth may 

 be this : a river carries its silt to the lowest hole in the crust it 

 can find ; the lowest holes near continents are those where the 

 crust is subsiding ; rivers thus deposit their loads in places of 

 crustal subsidence, but their loads do not cause the subsidence. 



Southerly Deflections Prevail over the Ganges 

 * Plains. 



Now let me tell you of the third discovery due to this 

 plumb-line. The Survey found that at 60 miles from the hills 

 this plumb-line hung vertically, and Pratt deduced the Theory 

 of Mountain Compensation. But when the Survey began to 

 extend their operations, a new phenomenon came to light, 

 which caused great surprise. All over the United Provinces 

 at distances exceeding 70 miles from the hills, this plumb-line 



