Chap. TV-] trichinopoly district— plant beds. 47 



is a remnant of the plant-bearing formation, the softer shales and friable 



sands having been denuded. The most notable instance of this occurs 



at Cullygoody, on the South-east boundary of the 



At Cullygoody. 



Trichinopoly formation, where an extensive boul- 

 der-bed, followed by a mass of fine micaceous shales and grey sands, with 

 intercalated bands of calcareous grit, underlies the coral-reef limestone. 

 These shales and sands bear so much resemblance to certain beds of the 

 plant-bearing group, that although I was unsuccessful in discovering 

 plant remains in them, I should have referred them to that group, did 



^ , . , . they not contain marine fossils, which renders it 



Beds Avith marine 



fossils. at least improbable that the beds are of contempo- 



raneous formation. The fossils of these beds are indeed, so far as they 

 are determinable, peculiar to this Cullygoody dejDosit, at least I have not 

 met with any of them in beds of the Ootatoor or Trichinopoly Group, 

 but a fragment of a helemnite, which bears some resemblance to an 

 Ootatoor species, interpreted by the fact that the genus only occurs 

 elsewhere in this district in beds of undoubted Ootatoor age, induces 

 me to believe that the Cullygoody beds are a peculiar local deposit of 

 that group. 

 The age of these plant-beds is a subject upon which I do not feel 



qualified to pronounce any decided opinion. The 

 Age of plant-beds, 



only fact to be gathered from their stratigraphical 



position in Trichinopoly is, that they are older than the Ootatoor Group, 

 or in other words, that they are not newer than the lower divisions 

 of the Cretaceous period ; the Ootatoor beds being, as is indicated by 

 their cephalopoda, probably of Middle-cretaceous age. Apart from consi- 

 derations founded on their contemporaneity with the Zamia beds of 

 Cutch, I see no physical reason to believe that they are very much older 

 than the Cretaceous formation. They have been indeed extensively 

 denuded, but I have met with no such unequivocal evidence of their 

 disturbance, as their prevalent dip of 6 to J 5 degrees is not higher than 



