88 CRETACEOtJS ROCKS OF S. INDIA. [PaRT II. § 1. 



garnet and magnetic iron, with some gi-ains of black mica : small pebbles of gneiss are also 

 sometimes included, and occasionally, though rarely, fragments of exogenous wood and shells, 

 (Gasteropoda and Bivalves) which, like the beds iu which they are enclosed, bear the greatest 

 resemblance to those of the Trichinopoly Group immediately overlyin£-. The beds have a very 

 low dip (2" to 6°) from the point where they first appear North-west of Garoodamimgalnm to 

 Kolokaunuttom, and as both dip and strike coincide almost exactly with those of the Trichi- 

 nopoly beds, the two groups are scarcely distinguishable, except by the presence of certain charac- 

 Reaembiance of Ootatoor teristic fossils in the latter, the most constant of which is the 

 and Trichuiopoly fossils. Chcmnitzia undosa, Forbes. A large number of fossils are common 



to the two groups, (sp. of Voluta, Natica, Area, ^c.,) or so closely resemble each other, that the 

 superficial knowledge which I had gained from experience in collecting them, did not 

 enable me to distinguish between them. 



About half a mile to the North-west of Kolokaunuttom, the beds are particularly rich in 

 fossils, many of them of species not met with elsewhere. The 

 Acteonelia beds. fossiliferous rock, which is exposed in a nullah, is a blue limestone 



crowded with small shells, the most delicate sculpture and polish of which are beautifully pre- 

 served; but both from the nature of the species and from the fact that all the Conchifera occur 

 in single valves, I have little doubt that they have been drifted to the position they now 

 occupy. Opisthobranchiate Genera, especially Acteonelia and Tornatella, are very abundant- 

 Also a Natica resembling N. pagoda, Forbes, but with a peculiar punctate marking like that of 

 CinuUa, and species of Voluta, Fusus, Eulima, &c. Most of these I have not noticed elsewhere, 

 but a characteristic Ootatoor Inoceramus is common, and many small bivalves, Cardium, Venta, 

 Astarte, &c., which are among the most abundant species, occur also in the lower beds of the 

 Trichinopoly group. An Acteonelia also, which is exti'emely abundant in some spots, and which 

 I have not met with elsewhere in the Ootatoor Group, occurs at the base of the Trichinopoly 

 Group, in the neighbourhood of Cullygoody. 



We have thus at this locality, both stratigraphically, lithologically, and palseontologically an 

 Apparent passage into the apparent passage between the Ootatoor and Trichinopoly Groupe, 

 Trichiuopoly group. ^j^^^^ qs I have abovc mentioned, were it not for the presence of 



certain characteristic species in the lower beds of the latter which nowhere occiir in the former, 

 and had we not within a distance of 2 miles a striking instance of the unconformity of the 

 groups, we might be led to believe that the passage existed in fact. The Kolokaunuttom beds 

 are the highest of the Ootatoor Group. Immediately to the North of Kolokaunuttom the 

 Trichinopoly beds begin gradually to overlap them, and in the neighbourhood of Shutanure 

 a sudden twist in the boundaiy of the former shuts ofi" all the higher beds of the latter. 



On the slope to the North of Kolokaimuttom, and in the broken ground on the Shutanure 

 u b ■ No th of Koio- ^^^^ °^ *^® ridge, these beds are well seen, consisting of the usual 

 kaunuttom. gj.ey sands and prominent calcareous bands, the whole almost 



without fossils. The sands show much false bedding. As we progress Northwards, beds of 

 this character come in irregular succession lower and lower in the group ; so that in spite of 

 the overlap of the Trichinopoly beds the outcrop of the coarser beds remains of about 

 the same width. The angle of dip is very low on the Kolokaimuttom slope, and is either 

 to the South or a few degrees East of South ; but in the nullahs on the Shutanure side 

 of the watershed the bedding strikes roimd to the North-east, and the dip increases to 



