StlPRA-NtJMMULIflC IDEPOSITS, 9 



nomenon as is evinced in the structure of the older formations now to 

 be described. 



3. SUPRA-NUMMULITIC DEPOSITS. 



There is very little to be said as yet regarding the rocks younger 

 than the nummulitic. In the Khasia region there is only a remnant of 

 them visible along the outermost spurs of the low flanking hilisj where 

 they exhibit the maximum of disturbance^ being quite vertical and folded. 

 In the absence of proper fossil evidence the distinction is at present 

 vaguely and provisionally made upon a general difference of lithological 

 characters. Among the younger rocks the most prominent is a thick- 

 bedded soft greenish-gray sandstone^ very like the common rock of the 

 Sub-Himalayan series. 



In the eastern portion of the plateau in North Cachar, there is a 

 great thickness and extent of these beds still quite undisturbed ; and it 

 would seem that in the adjoining mountain region the great ridge of the 

 Burrailj which far outtops the plateau^ is principally made of these rocks. 



Westwards, in the Garo region, this series is again well exposed; 

 but its thickness is very much less than in Cachar, and at the same time 

 the disturbance exhibited outside the area of the plateau is much reduced 

 in amount, and somewhat modified in form, as will be described further 

 on. The sandstone of Nonkalong in the Habiang Garo hills, from 

 which Captain Godwin- Austen made a collection of fossils,* and which 

 is within the high-level area, is probably the bottom of the supra-num- 

 mulitic series, as there seems to be a very decided denudation-un- 

 conformability between it and the underlpng nummulitic limestone. 

 The general parallelism of the groups is, however, maintained through- 

 out. 



* Among these Dr. Stoliczka recognises the genera, Conus, Bolium, Dentaliwm, Cardita, 

 Cwrdiwm, Tellina, Nucula, Leda, CueuUcBa and several others ; and remarks that none of the 

 species, so far as recognisable, appear to he identical with those known from nummulitic 

 beds of the same district. 



( 159 ) 



