Chap. IV.] trichinopoly district — ^plant beds. 



45 



The ground to the north of Coodicaud is much broken up by guUies, 

 and good sections of the plant-beds, consisting of 



Plant-beds North of =• 



Coodicaud. alternations of micaceous shales and grey sand- 



stones and grits, with great calcareous concretions, are everywhere 

 exposed. One of these concretions, about six feet in diameter, is repre- 

 sented in the accompanying sketch (Fig. 2). 



Fig. 2. Conceetion in plant-beds, near Coodicaud. 



The beds dip to the East and North-east, generally at a low angle, but 



sometimes as much as 15° to 20°. The plant 

 Diji of bedding. 



remains here are not well preserved : I was 



myself unsuccessful in meeting with any, but 

 Plant remains. 



Mr. Oldham was more fortunate. 



West of Coodicaud a few gneiss blocks are found in the lower beds of 



^ , , , , shale, and at one point a regular boulder-bed, con- 



Boulder-bed. ' r & ' 



sisting of little else than a heap of blocks of decom- 

 posed gneiss, is exposed in a small gully. CroAvning the high regur-covered 

 ridge to the North-west, the boulder-bed is again met with, its out-crop 

 being not less than a quarter of a mile in width, and extending up to the 

 edge of the overlying coral limestone. As usual it consists wholly of decom- 

 posed boulders, the interstices of which are filled with a fine gneissose silt, 

 similar to that of which the shales of the plant-beds are chiefly composed. 



