THE GRANITE. 53 



The features I have described seem to me most compatible with 

 the supposition that the introduction or formation of this trap was 

 cotemporaneous with the principal contortion of the series. When 

 examining the similar stratified series in Behar^ in 1863, I was led to 

 make an analogous conjecture regarding the trappoid and quasi-intrusive 

 rocks there. The evidence there for the, in great part, local origin of 

 the trap was supported oy the fact that in the older metamorphic rocks 

 close by there were little or no signs of similar intrusive rock. This 

 point of evidence is probably to be found in the Khasia hills. In 

 studying the metamorphic rocks of Western Bengal my colleague 

 Mr. M. H. Ormsby has made an analogous distinction between igneous 

 rocks more or less intimately associated with the contortions of the 

 strata, and later igneous rocks cutting all with little regard to pre-exist- 

 ing structure ; the former he indicated by the name of hypo-cotempora- 

 neous, or hypo-synchronous, a term that conveniently expresses the 

 opinion and the relation indicated. 



11. — The Granite, 

 It still remains to notice the granite, of which two principal 

 expanses occur. Within our area these are only found in contact with 

 the Shillong series ; but their limits to the east and west have not been 

 traced. The most northern of the two has been described as the granite 

 of Molim ; it extends eastwards beyond the area examined ; the road 

 between Maophlong and Shillong runs for some miles close to its western 

 and northern boundary ; between Lailangkot, on the south, and Shillong 

 it is five miles broad. The southern area seems much larger : its boundary 

 approaches from the north-north-west to near Surarim; here it bends 

 southwards, passing about half way between the scarp and the bottom of 

 the vaUey under Surarim ; at the head of the Nongpriong valley there is a 

 narrow slice of the granite exposed, the boundary passing westwards under 

 the cretaceous rocks. I did not fix the exact position of the south boundary 

 in the valley of the Bogkpani ; the granite is continuous there from 

 B 1 ( 203 ) 



