40 On the Red Marl Formation of Mysore. 



fetched theories, I prefer considering the formation to be in 

 the state in which nature formed it. 



Veins of hornblendic rock, arranged in globular masses, 

 sometimes traverse the red marl, as pointed out by Dr. 

 Clarke for what he calls basalt in the above rock. In a few 

 cases basalt dykes are seen in the granite, as in one instance 

 at Bangalore, and at Deonhully, but they never traverse the 

 red marl. 



Pisiform cellular laterite is common all over this formation, 

 it is composed apparently of small nodules of clay ironstone 

 of a red brown colour, cemented together by yellow fer- 

 ruginous paste. But I cannot agree with Lieutenant Baird 

 Smith in supposing it always to be a recent production, for 

 although I have found in many situations small portions 

 which contained apparently water-worn angular fragments of 

 rock, yet I have also more frequently found it where recent 

 aggregation was impossible, as for instance on the west 

 side of Yellavunkah, where the nodules are seen disse- 

 minated through the red earth for many yards round a 

 nucleus of laterite, which is also embedded evidently in situ, 

 and I have also frequently taken from the outside of a block 

 of hornblende rock (black granite) portions differing in no 

 essential from this laterite. 



In no work to which I have access do I find any descrip- 

 tion of a similar formation. Dr. Thomson in his Outlines of 

 Geology mentions that sandstone of the old red formation 

 occurs in the Ord of Caithness, probably covering granite ; 

 and Macculloch mentions the superposition of old red 

 sandstone upon granite in Caithness and Aberdeenshire. In 

 the want of more perfect descriptions it is surprising how 

 closely the description of the new red sandstone formation 

 of England applies to the tract in question. Brande (Outlines 

 of Geology) remarks, " that the appearance of the whole 

 may be described by the figure of a sea surrounding eleva- 

 ted islands, consisting of rocks of the subjacent series ;" in- 



