CHAPTER X. 



Later Tertiary and Recent Alluvial Deposits. 

 Under this heading five groups of formations have to be considered ; 

 the first is the Konkan laterite, an argillo-ferruginous deposit^ supposed 

 to be of sedimentary origin; the second group includes a series of 

 rocks of sedimentary origin, in which no fossils have hetherto been found, 

 but which, from their mode of occurrence and topographical position, are 

 supposed to be the remains of ancient fresh-water lakes. The age of 

 these is as yet undetermined, but they are certainly older than the 

 fourth group, which embraces the alluvial deposits of the existing rivers, 

 and probably also older than the third group, which is formed by an 

 ossiferous deposit of fluviatile or fluvio-lacustrine origin of great interest, 

 containing mammalian and other fossils ; of the former of which at least 

 one species is extinct. The fourth group inchides both the older 

 and newer river alluvia, which at present can only be recognized by 

 the respective levels at which they occur, as no organic remains were 

 found in the high level older alluvia. The position occupied by the 

 latter is of itself enough to prove that circumstances have changed the 

 face of the country considerably since they were deposited. The fifth 

 croup includes the older and newer marine alluvia of the Eonkan coast, 



1. — The Konkan Laterite. 



The reasons for considering this argillo-ferruginous formation as of 

 different origin from the Deccan iron-clay, which have already been given at 

 pages 200 and 201, are the vast diflFerencein the geographical positions 

 occupied by the two formations, and the presumption, based on analogy of 

 position of the Konkan laterite with that of the Malabar and Travancore 

 laterite, that the former is of sedimentary, and probably of marine, origin, 

 the Deccan iron-clay being regarded as a result of the alteration, by sub- 

 aerial ao-ency, of a volcanic rock. Evidence is wanted to confirm the 



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