GEOLOGICAL SURVEY OF INDIA. 281 



The tracts throughout the Indian Empire still awaiting geological 

 examination are of very large extent. In India proper, south of the 

 Himalayas, an area of about one-fourth is represented on the latest 

 " state of progress " map of the Geological Survey as having been 

 " mapped, reported on, and published." It is true that throughout 

 a considerable area thus represented, the topographical maps used 

 as a basis for geological surveying were very imperfect, and conse- 

 quently a more detailed survey may hereafter be necessary. But, 

 on the other hand, most of the tracts, such as coal fields, demanding 

 close mapping, have been completed, and an enormous area is occupied 

 by the alluvial deposits of the Indo-Gangetic plain and by the 

 Deccan trap, neither of which, so far as is known at present, 

 requires to be surveyed in detail. The remainder of the unsurveyed 

 area is occupied to a great extent by gneissose rocks, the examina- 

 tion of which has been postponed parthy because of the rarity 

 amongst them of useful minerals, partly because of the great 

 difficulties presented by them. 



It is very difficult to form a trustworthy comparative estimate of 

 the work that remains to be done before the geological mapping of 

 the Indian Peninsula can be regarded as fairly complete, but 

 probably about half the work of actual mapping remains to be 

 done. 



In the Punjab, Kashmir, and Sind, the progress has been greater, 

 though much of the work (as has been shown in the case of the 

 Salt range) will need revision. Baluchistan is almost untouched. The 

 North-western Himalayas cannot be regarded as nearly half finished, 

 and of course the range east of Garhwal is, with the exception of 

 a few sections, chiefly in the lower ranges, geologically unknown. 

 Of the countries east of the Bay of Bengal, some portions of the 

 Assam hills and the province of Pegu, with the southern part of 

 Arakan, have been surveyed, all the remainder of Burma, including 

 besides Upper Burma, Martaban, and Tenasserim, together with 

 the enormous tract of country between Burma, the Assam valley, 

 and Eastern Bengal, is unsurveyed. 



Roughly, it may be said that west of the meridian of Calcutta, 

 the mapping is half finished or nearly so ; east of the meridian of 

 Calcutta only a very small proportion of the area, certainly not 

 more than one-sixth, has been geologically surveyed. A large 

 amount of exploration and of reporting upon useful minerals has 



