>74 



HOLLAND : CHARNOCKITE SERIES. 



The hill on which this garnetiferous leptynite occurs is se- 

 parated from a number of quarries further east by a narrow tract 

 of alluvium running N.-N.-E. and S.-S.-W. 1 At the southern end of 

 the quarries the leptynite is again found associated with charnockite, 

 the junction line being obscured in a rubbish-covered gully. About 

 a mile E.-S.-E. of this point a further occurrence of leptynite associated 

 with charnockite shows a gradual passage from the former (No. 9/668) 

 to the latter (No. 9*669). This occurs on both sides of the central 

 mass of norite, which is thus fringed by leptynite and charnockite. 

 The facts revealed at this point leave little doubt as to the secondary 

 origin of the characters which serve to distinguish the leptynite from 

 normal charnockite. 2 



Fig. 5. Sketch of block occurring at A in fig. 4, and showing the gradual 

 passage of char no c nit e into leptynite. 



Between this hill and the quarries referred to above occur the 

 exposures of the peculiar biotite-bearingroek described on p. 158, near 

 which is found the graphite-bearing variety of the " intermediate " 

 group of this series (p, 152). 



The principal exposures of norite on the east side of the 



1 From these quarries the rock used in the Madras Harbour works has been largely 

 obtained. 



2 See also p. 142. For further evidence as to the formation of garnets from pyroxenes, see 

 Fee. Ceol. Surv. Jnd. t Vol. XXIX, p. 20. 



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