68 On the levels of Indian Coal Fields. [Jan. 



is seen protruding from beneath the lower strata of sandstone here 

 represented by a coarse conglomerate of boulders, imbedded in some 

 occasions in a matrix of felspar, as in the valley of the Calapany*. The 

 greenstone i, forms the whole declivity on the south side of the Bogapany, 

 down to the bed of the torrent which is formed of a glassy basalt, 

 apparently nothing more than altered masses of that portion of the 

 sandstone. formation which has been here entirely overthrown by the 

 causes just adverted tof. Ascending from the torrent along the pre- 

 cipitous face of the mountain to Muflong, the metamorphosed rock 

 gradually loses its columnar structure, and assumes the character of 

 granular slaty quartz. In the vicinity of Mujlong, this last form of 

 rock, which may be traced by several gradations into ordinary sand- 

 stone, rests on sienite in highly inclined masses. Sienite forms some 

 of the loftiest summits in this situation, but appears to pass, on declivi- 

 ties, into a rock formed chiefly of felspar in a fine granular crystalline 

 state, with a little quartz J; and enclosing granitic masses which under- 

 go concentric decay, and occasionally beds of mica, and sometimes of 

 quartz much comminuted. This constitutes the principal formation 

 over which the road extends from Mairang into the valley of Assam. 

 Somewhere on either side of the lower portion of this declivity, coal 

 measures have been detected the same as on the Bengal face of the 

 mountains, but accompanied with newer sandstones containing salt 

 springs in addition to fossil trees and detached fragments of coal. 

 Limestone, agreeing in mineral characters and probably in fossil con- 

 tents with that of Cliirra, also occurs in this side of the mountains ; 

 but the relative position of the beds, as well as all other important geo- 

 logical features here remain unexplored§. 



* This is a small but precipitous river valley, met with in the table-land 

 between the Serarim and the Bogapany. 



f It is always satisfactory on such occasions to find the views of different 

 observers agree in ever so limited a degree : I may therefore remark that Sir 

 Edward Ryan and Mr. Cra croft, who on distinct occasions crossed this 

 portion of the Kasya mountains prior to the visit of the Assam deputation, also 

 found rocks which they denominated basaltic. No 21 in Sir Edward's collection 

 of specimens presented to the Asiatic Society's museum' is named' basaltic 

 quartz' from the bed of the Bogapany ; and is the same as the glassy basalt 

 abovementioned. Mr. Cracroft's collection of specimens from between 

 Mufiong and Serarim also contains a ' basalt' as well as ' a coarse quartzy 

 sandstone' — (Vide Journal of the Asiatic Soc. Vol. III. 296) which is thft 

 metamorphosed sandstone here spoken of. 



X Described in my geological catalogue as primary sandstone. 



§ Figs. 25, 20, 21, and 15, Plate 2, were found in a small quantity of the Assam 

 limestone which had been brought to Gowahatti for the purpose of making 

 lime : all these but 15 have heen found in the Chirra limestone also. 



