1845.] Notes on the South Mahratta Country, fyc. 299 



lately been discovered in the sandstone of the Goond country, and 

 traces of it exist in the sandstone N. W. of Nagpore. 



Laterite. Next in order of superposition to the sandstone comes the 

 overlying trap ; but adopting the arrangement of Lyell, I shall place 

 it and the granitic rocks apart from those that have a confessedly 

 bedded structure. 



Laterite was classed both by Voysey and Christie with the overlying 

 trap ; by the former as a volcanic rock. Christie has not given an 

 opinion as to its origin. It has been thought of volcanic origin, 

 principally from its apparently unstratified and non-fossiliferous charac- 

 ter, and being frequently associated with trap rocks. It however oc- 

 casionally possesses a distinctly stratified and conglomerate character, 

 and passes into a loose coarse sandstone, as at Pondicherry, imbedding 

 silicified wood, and at Beypoor, on the Malabar Coast it passes into 

 a loose sandstone imbedding layers of lignite. General Cullen was 

 the first to discover lignite and carbonized seeds in the laterite of 

 Quilon and Travancore. He now writes me, that he has discovered ex« 

 tensive beds of lignite in the laterite formation of these provinces. 



Some geologists suppose it is the result of the weathering still in 

 progress of granitic and trap rocks in situ. The fact of its imbedding 

 rolled fragments of sandstone when resting on granite, and the beds of 

 lignite and silicified wood it contains, militate strongly against this 

 theory : and independently of these facts, nothing is more common in la- 

 teritic tracts than to see a hill of trap or of hornblende, gneiss or other 

 hypogene schists capped with a thick bed of laterite, while the adja- 

 cent hill, composed of an exactly similar rock, and equally exposed to 

 the action of the weather, is quite bare of laterite. I have examined beds 

 of laterite resting on trap and amygdaloid imbedding calcedonies and 

 jasper, but have not hitherto detected in the former any fragments of 

 these tough silicious minerals, which are found to resist successfully 

 even the attrition of the most rapid streams of India, long after the 

 imbedding trap has disappeared and been lost in alluvial sands, and 

 carried across the Peninsula into the bed of the ocean. 



Their occurrence, however, particularly at the point of contact, would 

 not prove that the laterite was formed from the upper portions 

 of the subjacent trap weathered in situ. A detrital and mechanical 

 origin like that of the sandstone, would carry into it the harder un- 



