Economic Geology. 23 



are not favourable for the employment of the method of 

 boring. It does indeed sometimes happen that when such 

 districts have been subjected to violent disturbing forces, 

 when the strata have been fractured and upheaved, and 

 faults formed, that large bodies of water collect beneath the 

 surface; but these disturbances being local, and most fre- 

 quently furnishing themselves natural drains for the collect- 

 ed waters, their occurrence does not remove the many obsta- 

 cles primary districts present to the success of boring expe- 

 riments. The individual rocks of which these are composed 

 being of a close, hard, crystalline structure, and exhibiting 

 no alternations of porous with impervious strata, the only 

 chance of success would be in meeting with some interior 

 sheet of water, but this is far too vague to warrant the 

 expenditure of time and money which would necessarily be 

 incurred, and it may therefore safely be concluded as a 

 general principle, that boring operations ought not to be 

 undertaken in primary formations, since the natural machine- 

 ry on which their success depends is not to be found in 

 these. The geology of India, like its history, carries us 

 back to the earliest epochs, and primary rocks constitute a 

 large portion of its framework. This is especially the case 

 in southern India, where granitic rocks are almost universal. 

 These are generally covered at low levels with nothing 

 more than a bed of derivative sand by which water is readi- 

 ly absorbed, and may again as readily be recovered by com- 

 mon wells. Every attempt however which has hitherto 

 been made (and there have been several) to increase the 

 supply of water in these localities by boring through the 

 hard and massive rocks has naturally failed, and the failures 

 are easily explicable from the circumstances above stated. 



The alternations of porous with impervious strata in later 

 sedementary deposits, and the continuity of these over ex- 

 tensive areas, with their occurrence at high as well as low 

 levels, furnish us with those dispositions which most favour 



