DETAILED ACCOUNT OF SOME RECENT EXPERIMENTS. JQ 



water-bearing stratum would be pierced near the base of the 

 series where it rests on gneiss. The pressure might not be sufficient 

 perhaps to cause a flow of water, but it would be within easy reach 

 of pumps. 



Sections situated a few miles north and north-west of the artesian 

 boring show that the basement beds of the Gondwanas consist of a 

 considerable thickness of permeable felspathic grit. The boring 

 runs through a great thickness of black and dark grey carbonaceous 

 clays which probably overlie that sandstone. 



The Gondwana rocks exposed to the eastward and northward 

 have been described by Mr. Foote. 1 They belong to the upper 

 Gondwana stage. The rocks exposed belong mainly to the upper 

 part of the series and consist of light- coloured shales ; clays and 

 sandstones. But in the boring they are found to be underlaid by 

 the above mentioned dark grey and black carbonaceous shales ; in 

 fact, it was through the boring that the existence of these dark 

 clays first came to be known. 



At the date of Mr. Foote's visit the boring had been carried 

 through a considerable thickness of these impervious clays. It had 

 been stopped for want of funds, but Mr. Foote considered that the 

 water-bearing stratum was not far off, and that the boring should be 

 continued until water is struck, or until the underlying gneiss is 

 reached. Moreover, Mr. Foote pointed out that some of the dark 

 carbonaceous clays are bituminous, and that, even if the boring were 

 unsuccessful from the point of view of water, yet it might reveal 

 the existence of coal seams or of bituminous shales worth distilling, 

 or of valuable fire-clay. It would be, besides, of great scientific 

 interest. 



Since Mr. Foote's visit the boring has been deepened over 

 ioo feet : in October 1899 it had reached a depth of 430 feet. Yet, 

 the felspathic grit has not been reached, although a small band of 



1 " On the Geology of parts of the Madras and North Arcot districts lying north of the 

 Palar River." Mem. Geol. Surv. Ind., Vol. X, Part I. 



( 79 ) 



