GEOLOGICAL NOTES ON ASSAM. 39 



during tte lapse of incalculable time."^' North of the station the rounded 

 hills are confluent^ and in the road-cuttings there all the intermediate stages 

 of the phenomenon are seen ; patches of the coal and shales are found 

 crushed and contorted in a manner that it would be scarcely possible to 

 account for in any other way, seeing that the underlying rocks are 

 quite unbroken. It is probable that the limestone had never been as 

 thick in this position as we now see it to the south. So very exceptional 

 a process of demidation would be well worthy of mention in geological 

 manuals. If all the limestone had been removed from here_, as a large 

 proportion of it has been, it would have been very puzzling indeed to 

 account for the resulting appearances. 



From the descriptions already given, it will have been apparent 

 that very marked stratigraphical conditions coincide with the orogra- 

 phy of the Cossyah Hills. The undisturbed rocks to which the 



Structural features of ^'^"^^^^ ^'^®^ ^^^^ ^^ i^^ peculiar features were 

 the southern scarp. deposited upon and against a raised area having 



about the same general form as the actual range; they seem to 

 be but the remnant of an overlap at the edge of a basin of deposi- 

 tion. Besides the very rapid thickening of the deposits to the south- 

 wa,rds, there is from some distance north of Cherra a constant small 

 inclination of all the strata in the same direction ;t it may be due 

 to original deposition. Additional conditions have, however, super- 

 vened to rejDroduce the ancient line of denudation. Coincident with 

 the extreme southern limits of the table-land scarp in this position, 

 there is a well marked axis of uniclinal flexure — an induced bend in the 

 strata — whereby the top rocks are rapidly brought down to the level of 

 the plains. It is of interest to fix correctly the nature of this feature 

 of structure; for it is in marked contrast with others in aj)parently 

 analogo^^s orographical circumstances. Below the general run of the 



* Mem. Geological Survey, India, Vol. I., p. 1 18, &c. 

 t Mem. Geological Survey, India, Vol. I., p. 120, &c. 



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