KHASIA GREENSTONE. 51 



remote times a region of granitic intrusion and a centre of metamorphos- 

 ing influence. 



If I were to conjecture an identification of the Shillong series with 

 rocks known in other parts of India, I would point out the decided 

 similarity of composition, of order of succession, and of condition to the 

 quartzites and schists of Behar, as seen in the hills of Rajgir and 

 Gya. 



10. — The Khasia Greenstone. 



Within the area of the Shillong series, at least in its middle region, 

 eruptive rock occupies nearly as much place as either of the sedimentary 

 groups. The high road between Surarim and Maophlong passes continu- 

 ously over greenstone for about half the way, with the exception of about 

 fifty yards on the Maobelarka ridge, where a gap is cut through the cap- 

 ping of cretaceous conglomerate : from near the top of the descent into the 

 valley of the Kalapani, over the Maobelarka ridge, along the vaUey 

 of the lesser Kalapani, across a branch of the Maokaleng ridge and 

 down to the very bottom of the deep glen of the Bogapani, the greenstone 

 is perfectly continuous for a distance fully five miles. This line is no 

 doubt oblique to the run of the rocks ; but in places the outcrop of the 

 greenstone is certainly more than a mile wide ; and locally it reaches to the 

 full mean height of the plateau. It is undoubtedly an igneous rock, a 

 dense, basic trap in which the felspathie element is very subordinate. 

 It afiects various structures, angular and spheroidal, rarely sub-columnar. 



It is the gisement and the allure"^ of this rock that are obscure. 

 I could nowhere discover a sign of any portion of it being cotempora- 

 neous, as interstratified, with the sedimentaries ; nor does itself ever betray 

 a bedded arrangement. Lithologically, moreover, it has none of the 

 characters of subaerial volcanic rocks. It is then intrusive; yet, 

 * It is with some compunction I make use of these foreign words ; but I have often 

 sought in vain for English equivalents. By gisement I mean here the circumstances of 

 arrangement proper to the rock— whether bedded or amorphous and intrusive. By allure I 

 mean the external relations (behaviour), to associated rocks, 



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