106 CRETACEOUS ROCKS OF S. INDIA. [PaRT 11. § 1. 



tliat of tlie escarpment of the Blue Mountains of Sydney, which 



Mr. Darwin regards as a great upraised bank. Mr. Darwin, in the 



works 1 have quoted, does not mention the nature of the sediment, banks 



of which stand at the high angles of 40° and upwards, but we may notice, 



as in accordance with the well known rule, that the coarser the material, 



the steeper its slope of equilibrium, that the beds of the Ootatoor Group 



which have the highest continuous dip, are precisely tlie coarsest in the 



formation. 



Reviewing the whole of the above argument, there can be, I 



^ ^ ^ ^ „ _ think, but little doubt that the great mass of 

 Ootatoor Group com- ' o 



parativeiy uudisturbed. j.^^^ Qotatoor beds have been almost undisturbed 

 since the period of their deposition. The fault or faults that cut off the 

 beds to the South are, I believe, extremely small in amount, so much so 

 that they might have been quite overlooked, except for the amount 

 of tilting the beds exhibit at one spot where they are close to the 

 wall of the fault. On a first hasty examination I believed the disturb- 

 ance to be much more important, and hence the erroneous note insert- 

 ed in my Report on the Nilgiri Hills.* But that the disturbance in 

 question had any connection with the upheaval 



The neighbouring; hill , .,, . -^ . , 



groups therefore pre-ex- of the great hill groups IS, i am now convmced, 



°' quite out of the question ; for any upheaval of such 



hill masses must necessarily have been evidenced by extensive faulting 



over a wide surrounding area. These hills must have stood, as they 



now stand, somew^hat higher, it may be, and with smaller gaps and 



shallower valleys forming the land bordered by the Ootatoor sea. 



That any great change of form beyond that due to the perennial 



wastino- of winds and waters has touched them, we have no reason 



whatever to believe, and this fact once admitted, we may assume with 



great probability thai within the same period no part of Southern 



India has undergone any great convulsion. 



* Memoirs Geological Survey of India, Vol. I., page 283. 



