60 CRETACEOUS ROCKS OF S. INDIA. [PaRT II. § 1. 



Cretaceous rocks that extends across the Madras road at Seragancior, a series 



of little outliers of the Trichinopoly Grouprest on the disturbed beds of 



the Ootatoor Group, which, at Seraganoor and one or two olher places 



are seen to be faulted against the gneiss. In the midst of one of these 



little outliers, close to the spot marked on the map as the site of the 



(now extinct) village of Muddam, a little boss of the corallifei'ous 



foim of the limestone appears in situ, as shown in the figure. Its exact 



relations to the Cretaceous rocks are not ascertainable, and I believed at 



first, judging from the faulting of the Ootatoor 

 Its age discussed. 



beds close by, that it furnished an indubitable 



instance of coral-reef limestone of Trichinopoly age. Although the boss 

 itself is quite insignificant in size (only a couple of yards or so in diame- 

 ter), it Avas of great importance to ascertain the truth of this inference 

 on account of the bearing that the fact, if established, would have on any 

 inference as to the age of the larger and more important ridges of similar 

 limestone at Cullygoody, for if coral-reef limestone, undistinguishable 

 from that which we have shown to occur frequently at the base of the 

 Ootatoor Group, could be shown to have been also formed at the com- 

 mencement of the Trichinopoly epoch, the negative reasons which lead 

 us to assign a pre-Ootatoor age to the Cullygoody limestone, would 

 entirely fall to the ground ; and thus, as I have shown a few pages back, 

 the age both of the limestone and of the fossiliferous boulders at that 

 locality would become involved in greater doubt than ever. On this 

 account, therefore, I searched carefully for any evidence that could aid in 

 deciding the age of the little Muddam boss, and the result, founded on 

 the following grounds, is that there is no reason to believe this cate 

 exceptional in point of age. 



The Ootatoor beds are, as I have stated, unmistakeabl}" faulted against 



J. .^ r^ ^ the gneiss at Seraganoor ; and at one or two other 



Reasons for its Oota- ° ° ' 



toor age. places on this boundary, between that village and 



Paroovalapoor, there is good reason to infer a similar disturbance, but 



