Chap. VI.] trichinopoly district — ootatoor group. 89 



about 15°. The only fossils I met with in the Ootatoor beds on this side were Pccten 

 5-costatiis and a small Ostrea (O, columba ?J and these were thinly dispersed through 

 certain of the calcareous bands. 

 Between the forks of the Murdayaur, North-east of Shutanure, the same beds dip East- 

 Higher beds at Shutamire. south-east about 20° and contain a few Nautili, (N. Hux- 

 leyanus) a species which occurs abundantly in the neighbour- 

 hood of Moonglepaudy and Cooniun, and also in the Trichinopoly beds above. The beds 

 maintain the same character as far as Audanore, disappearing bed by bed as traceable on the hill 

 side beneath the Trichinopoly limestone. 



It is important to notice that the general strike of the upper beds of the Ootatoor Group does 

 Divergent strike of higher ^*^^ hannonize with that of the lower, nor is there, as I have be- 

 ^^^^- fore observed, any such variation in the amount of the general dip 



of the group as would account for this difference, supposing that the whole group had 

 been originally deposited of equal thickness horizontally, and subsequently imequally de- 

 pressed towards the South-east. The strike of the upper Ootatoor beds between Garooda- 

 mungalum and Kolokaunuttom nearly coincides with that of the Trichinopoly group, and is to 

 the North-east, while that of the corresponding bottom beds from Oogalore to Kaui-ay is about 

 North by East, yet the average dip between Oogalore and Garoodamungaliim, where the 

 group is narrowest, does not appear to be greater than that between Kauray and Ko- 

 lokaunuttom ; these anomalous features of the stratification are not, moreover, confined 

 to the area I have just described, but prevail throughout the group. I content myself 

 at present with noticing the fact : the deduction which I di'aw from it, in conjunction 

 with other circumstances, will be seen in the sequel. 



Crossing the North branch of the Murdayaur nullah, we enter upon what is jgar excellence 

 the fossiliferous region of the Ootatoor beds. I have mentioned above that to the East of Cull- 

 paudy we met with the first indications of a richer fauna, in the occurrence of certain forms of 

 Cephalopoda. 

 Between Cullpaudy and Maravuttoor the bottom beds consist of soft shale and clay, with 

 Lower beds— Cullpaudy to ^<^^ bands of yellow Umestone, the latter filled with fossils of 

 Maravuttoor. several species. In some broken ground near the little tank about 



half way between the two villages some good sections of these beds are exposed close 

 to the gneiss, exhibiting the very irregrdar bedding which generally characterizes the 

 bottom beds. Owing to the small extent of the sections at any particular spot, and the 

 partial obliteration of their real character by the unequal destruction of the hard and 



soft beds, the existence of this irregularity is not immediately 



Irregular bedding. <-> j j 



apparent, and the high dips ranging from 6° to 25°, and 



sudden twists in the direction of the strike might be attributed to plutonic disturb- 

 ance. There i:, however, no clear evidence of anything of the kind; and the irre- 

 gular changes and alternations in mineral character remarked when beds are followed 

 along or across their local strike ; the absence of fractures ; and the fact that the irreg-ularities 

 in question di m inish rapidly as we leave the immediate vicinity of the gneiss, convince me 

 that the irregularities noticed are due solely to the formation of banks, by current action and 

 eddies during the deposition of the beds. Of the deceptive appearances often presented by 

 these beds the accompanying sketch (Fig. 9.) of a bed of limestone resting with apparent 

 unconformity upon what appear to be finely laminated clays, gives a fair illustration. 



M 



