tERTlARt AND UECJcNT DEPOSITS. 225 



second reason, but no doubt appertains to the first. It is quite clear 

 that this Konkan laterite cannot be the equivalent in ag-e of the "summit 

 bed^^ iron-clay which caps all the high peaks and ridges of the Sahyadri 

 mountains in the Belgaum and South Kolh^pur countries, even supposing 

 (as was done by Dr. Carter in his Summary of the Geology of India, 

 page 744!), that the low level laterite represents an altered volcanic rock. 



There is no reason for supposing that the iron-clay formation did 

 not extend far to the westward of the present western edge of the 

 highland region, possibly across or even beyond what is now the 

 Konkan lowland, and that the iron-clay was not denuded away by the 

 same agencies which cut away some 3,000 feet or more of the 

 underlying trappean rocks. The Konkan laterite, if an altered trap- 

 flow, as supposed by Dr. Carter, is either vastly older than the 

 " summit bed " iron clay, for it belongs to the very base of the Deccan 

 trap series, or if younger it must be younger by the whole of the period 

 occupied in the destruction of the more than 2,000 feet of trappean rocks 

 shown to have been denuded away after the conclusion of the trap 

 period, and formation of the summit-bed, whatever its origin may have 

 been."^ The formation of the Konkan laterite and summit-bed cannot 

 have been simultaneous, or else there would be evidence of a great break, 

 and consequently great unconformity, between the summit bed and the 

 upper basaltic flows, for the surface of the latter could not have re- 

 mained untouched by denudation during the period in which the great 

 scarp was being formed, and the summit would not have occupied the 

 level surface it now does. The fact that the Konkan laterite lies uncon- 

 formably on the Deccan trap (see section 6, Plate VIII) militates strongly 

 against the idea of the laterite having been formed by alteration of a 

 trap-flow in situ ; moreover, there are, underlying the laterite at 

 Ratnagiri, certain clays (described in the last chapter) containing lignite 



* There is not a tittle of evid ence of any outpouring of the Deccan traps having 

 taken place subsequent to the close of the Deccan period, which was long anterior to the 

 completion of the denudation of the Konkan area. 



2e ( 225 ) 



