53 FOOTE : GEOLOGY OF THE BELLARY DISTRICT. 



much greater prevalence of joints in the former case has also very 

 largely assisted in the work of destruction. 



Very marked and interesting illustrations of the power of weather 

 Water holes on the action along lines of jointing are, however, also 

 Fort hil1 ' to be seen on the top of the Fort hill in the 



shape of the water holes which have been utilised as cisterns. In 

 every case the weathering has worked along lines of jointing and 

 produced the remarkable holes which are so useful in holding rain 

 water, and of which the native builders availed themselves so fully by 

 increasing the water-holding capacity by dams. 



Some people seem to think the constant supply of water in these 

 holes a rather mysterious phenomenon, whereas it is in reality a very 

 simple one. The several catchment areas which supply the holes 

 are more than large enough to fill them in good rainy seasons, and 

 the larger holes are so deep that their stock of water cannot evapo- 

 rate more than partially before they get a fresh supply from the skies, 

 and thus never run dry in a normal succession of seasons. There 

 is then no need to appeal to occult causes, such as natural artesian 

 action, pressure derived from the Copper mountain, or subterranean 

 syphons connected with mysterious water stores at unknown depths^ 

 goodness knows where ! 



The depth to which the granitoid rocks are cut up by jointing is 



a question of some interest, but one on which light is hard to obtain. 



Judging by the appearance of the jointing seen in the rocky hills, 



Jointing in undecom- the depth might be supposed to be very great ; 



posed granite. ^ th j g does nQt geem to be ^ cage ever y_ 



where : at least an illustration of this was met with in Bellary itself in 

 December 1885, when the rock-cut basin of the Mainwaring tank op- 

 posite the new Collector's cutcherryhad been deepened by extensive 

 quarrying, and a large and a perfectly fresh surface of undecom- 

 posed granite exposed to a depth of probably 6 to 8 feet below the 

 original rock surface. The hard fresh surface was seen to be traversed 

 only by tiny crannies, barely large enough to be seen, and too small 

 to have their bearings taken accurately, as they did not show for 

 sufficient distances. 



( 58 ) 



