Chap. XI.] cuddalore sandstones. 175 



affording the only instances of tlie visible junction of the two for- 

 mations that I met with either in South Arcot or Trichinopoly. The 

 base of the Cuddalore beds, which are here nearly horizontal, is 

 marked by a thin band of hard ferruginous shale. Above this, in the 

 base of the beds, which are everywhere somewhat ferruginous, occurs 

 a conglomerate full of small pebbles of quartz and gneiss. A few frag- 

 ments of silicified wood are also met with, but neither in such abund- 

 ance, nor in such large masses as in the beds of Trivicary. The 

 Cretaceous rocks in the lower part of the section are composed of pink 

 and white sands, chiefly to be distinguished from the overlying Cuddalore 

 beds by their finer grain, and the occasional, though rare, occurrence of 

 an intercalated fossiliferous band. 



The Cuddalore beds are coarse in grain, consisting of comminuted 



garnet, quartz and magnetic iron, with specks 

 Miaeral character. p i i • 



of dark mica cemented by ochreous clay and 



kaolin, the former probably derived from the Cretaceous rocks ; the latter 



from the felspathic portions of the gneiss and the associated granite 



veins. 



To the East of the Red Hills the beds composing them are well 



Eastern slope of Red ^een, where the high road from Madras to Pondi- 



^' cherry decends the little escarpment which forms 



their boundary against the alluvial deposits of the coast. The best and 



most continuous section is, however, seen in a nullah which drains into 



the sea at Bommayapaleiyam, after cutting through the Cuddalore 



beds for about a mile, to a maximum depth of 20 feet. The rocks seen 



in this nullah are deep-red sandstones, with occasional lenticular patches 



of conglomerate of a lighter color. The whole are false-bedded, and I 



did not observe any case of true bedding from which the general dip 



Gould be ascertained. Along the coast the formation terminates in a 



very decided escarpment, running immediately to the West of the coast 



road, only distant about a furlong, or, at the utmost, a quarter of a mile 



