32 mallet: coal-fields of the naga hills. 



itself. The total thickness of the group is possibly much greater, but the 

 rocks above the section are completely covered. 



Recent conglomerate and clay, very similar in appearance to the 

 Dihiug beds, cover them in places, but the latter dip at about 20°, the 

 recent beds resting on them horizontally and unconformably. 



Beds, perhaps referable to the same epoch as the Dihing con- 

 glomerates and clays, are met with in some of the rivers to the westward, 

 but being overlaid by alluvium, they are not exposed over any consider- 

 able area. In the Taukak, some distance north of the hills, beds of blue 

 clay with an occasional band of coarse, but slightly consolidated sand- 

 stone, are exposed in the river banks. These are generally horizontal, 

 but dip locally at 5 to 10 degrees. They may be recent. In the 

 Saffrai the highest beds visible, next the coal-measures, are of conglome- 

 ritic sandstone with coal pebbles, perhaps on the same horizon as that in 

 the Dibing, and therefore just at the base of the strata in question. In 

 the Dhansiri. also, about half-way between Bor Pathar and the Nambar, 

 some horizontal conglomerate and sandstone are visible which contain 

 abundance of silicified wood, some of the stems being a yard in diameter 

 and four or five feet long. 



That the Tipdm and Dihing beds belong to the great ' Sub- 



„ _. , , Himalayan' series, which stretches along the entire 

 Age of Tipam and -^ ' » 



Dihing groups. jj^se of the Himalayas, with, as far as we know, 



hardly a break from the Indus to Assam, does not admit of any 

 doubt. North of Dibrugarh, Mr. Medlicott found the series in full 

 force, consisting, as it also does in British Sikkim and the Punjab, 

 as well as in the Naga Hills, of a great accumulation of soft 

 massive sandstones with occasional partings of clay, and passing above 

 into great beds of conglomerate.''^ The similarity in the section at once 

 suggests that the Tipam and Dihing groups may be, as they probably 

 are, the Assam representatives of the ' Nahan ' and ' Sivalik ' groups of 

 the Punjab. But with so many long gaps across which the rocks 



* Vol. Ill, pt. 2, p. 114^IV, p. 393— XI, p. 45. 

 ( 300 ) 



