168 KHASI HILLS. 



it is no easy task to unravel its complicated structure, or to obtain a 



clear insight into the causes which have produced it. 



I shall here briefly enunciate a few of the principal conclusions 



resulting from a general review of the previous 

 General conclusions. 



descriptions of the geological structure of these 

 hills. These are : that the general basis of the -range is srranite ; rest- 

 ing upon it is a series of metamorphic rocks, gneiss, micaceous slates, 

 quartz rocks, &g., which have been greatly altered, disturbed and con- 

 torted by the granite which now supports them ; that in connection 

 with these changes there appears to be evidence to show that the line 

 of greatest elevation caused by this granite, or rather by the forces to 

 which this granite is the index, had a direction East and West. Sub- 

 sequently to these disturbances and alterations of the older slates, these 

 rocks have been subjected to long-continued and great wear and denu- 

 dation ; and upon their degraded surface was deposited a series of beds 

 of sandy and earthy character, of varying composition, but in the aggre- 

 gate, of considerable thickness, which have subsequently been subjected 

 to great alteration. Another interval of considerable duration must now 

 have occurred, during which disturbing forces were again exerted ; 

 for, upon the upturned and degraded edges of these schistose and 

 quartzose beds, others have been formed of very different character, the 

 prevailing composition of which is sandy, and which, as a mass, give 

 abuadaat evidence of being shallower water deposits than the lower beds. 

 Again disturbances have taken place, contortions of these beds 

 have been forcibly produced by the exertion of great forces of intru- 

 sion and pressure; and these forces appear to have been accompanied, 

 if not produced, by the exhibition, on a considerable scale, and over 

 a considerable area, of volcanic-like masses, which have been emitted 

 in a highly heated condition, and have consequently exerted those 

 modifying effects which might be expected to result from such an 

 exhibition of heated masses on the large scale. 



