Stone Implements in lateritic formations. 5 



the brigade ground at St. Thomas's Mount, where the surface 

 has been less eroded, the bed may be seen in numerous bal- 

 last pits to have a thickness of 2-3 feet and occasionally to 

 assume the true conglomerate character. This laterite must 

 be considered as an outlier of the more extensive spreads 

 occurring south of the great Chembrumbaucum tank near 

 Poonamallee. 



The Implements discovered in such large numbers north 

 of Trivellore in the Atrumpakkam nullah valley are derived 

 from beds of lateritic conglomerate which are probably 

 younger than the typical laterite occupying extensive tracts 

 of higher ground in the immediate neighbourhood. 



These higher lying laterite conglomerate beds however 

 themselves yield numerous specimens of worked stones 

 identical in type with those from the low level conglomerates- 

 The reasons for regarding the latter as of later date will 

 be considered farther on. 



Finally, Implements have been obtained from sandy 

 quartzite gravel and shingle beds between Stripermatoor and 

 Conjeveram, but none have been found in situ in those 

 deposits. 



The discovery of Implements in various localities and 

 formations in North Arcot District was made by my colleague 

 Mr. King, whose description of them will be found appended 

 to this paper. 



The most instructive sections shewing the relation of the 

 low level Implement-bearing-conglomerates, occur in the 

 banks of the Atrampakkam nullah and of the various gullies 

 connected with it, several of which were formed by the 

 bursting of the large Numbaucum tank. 



Immediately below the old ruined pagoda already referred 

 to is a capital section cut by a gully formed through the 



