8 HATCH: THE KOLAR GOLD-FIELD. 



course of mining operations. They are typical unaltered dolerites 

 or diabases evidently of much more recent origin than the rocks in 

 which they are intruded. Under the microscope they are seen to 

 consist of fresh lath-shaped felspars and granular augite in approxi- 

 mately equal proportion. They closely resemble the dyke-rocks 

 described from other parts of Southern India, which are regarded by 

 the Geological Survey of India x as underground representatives of 

 the Cuddapah lava-flows. 



The specimens collected by me in the field were sent to the 

 office of the Geological Survey in Calcutta where they were cut and 

 examined under the microscope by Mr. T. H. Holland, officiating 

 Superintendent of the Geological Survey. His notes are appended 

 to this report. Thanks to the kindness of Mr. W. F. Smeeth, acting 

 State Geologist to the Mysore Government, I have also had the 

 privilege of examining the collection of rock-slides made from speci- 

 mens collected by the officers of the Mysore Geological Department. 



1 Rec. Geol. Surv. Ind., Vol. XXX (1897), p. 16, and Quart. Journ. Geol. 

 Soc, Vol. LIU (1897), p. 405. 



