192 PKOCEEDINGS OP THE GEOLOGICAL SOCIETY, 



the plains of Northern India got deposited and attained their present 

 state. 



How the enormous mass of debris was formed which is now spread 

 over the plains of India to as yet unknown depth I am not pre- 

 pared to give a decided opinion ; but, judging from what we see before 

 us, I cannot help thinking that most of it must have undergone 

 disintegration more than once. Possibly glacial action has aided in 

 grinding up the older rocks ; but such a force would leave this debris 

 in angular masses, not in rounded boulders or as sand and clay .Most 

 probably, however, a " pluvial period " * must have succeeded to wear 

 down this mass into its present state, while this same power of water 

 could carry forward this mass of matter and deposit it as we now 

 find it. The foregoing statements, I hope, wiU explain how this 

 matter comes to be deposited in alternate strata of sand and clay of 

 irregular thickness, as the boring here at Umballa shows. 



The level of the ground where this boring took place is 905 feet 

 above the level of the sea ; and as the tubes have been sunk to a 

 depth of 455 feet, the bottom of the tubes is now 450 feet above 

 the sea-level. For a distance of 385 feet, pipes of 9^ inches diameter 

 were sunk ; and the remaining 70 feet was got by sinking 7-inch 

 pipes inside them ; thus the second set were relieved of side pressure 

 for nearly five sixths of their length. The pressure exerted when the 

 sinking of the first set of tubes was brought to a stand-still was 

 equal to 64 tons, aided by taps from an iron ram ; but as it was con- 

 sidered dangerous to apply any greater force, the second set of 7-inch 

 pipes was forced down 70 feet further, when they also were brought 

 to a stand-still by the breaking of the joint of the last pipe ; but 

 this was not before a pressure of 80 tons was exerted. The stoppage 

 was owing to the lower pipe getting off the perpendicular ; and it is 

 supposed that this was in consequence of its having got among 

 boulders. 



The soil passed through, as will be seen by the appendix, has been 

 alternate layers of clay and sand, sand and clay, of various thickness. 

 Water was reached at 27 feet below the surface ; and though all 

 throughout the soil was water-bearing, yet in no case did it appear 

 to be under pressure, except in one instance under a bed of kunkur ; 

 for not only did it not rise in the tubes, but latterly water had to be 

 almost constantly poured down the tubes to prevent the sand rising 

 in them. Some trials were made to test the supply at different 

 depths ; but the quantity was quite inadequate for any purpose ; so 

 as yet the result is nil as to reaching a good water-supply. 



This want of upward pressure clearly goes to show that there can- 

 not be any extended bed of clay as far as is yet reached, but that 

 the deposits have aU been in patches ; for otherwise there must have 

 been a rising of the water in the tubes, due to the difference of level 

 between the points where the water was tapped and where it entered 

 below the clay stratum on its upper or northern extremity. The 

 deduction to be drawn from this appears to be that these strata 



* Q. J. G. S. vol. xxiv. p. 120, 1868: Tylor, "Pluvial Period." 



